Update dependency undici to v6.27.0 [SECURITY]

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
undici (source)	6.19.2 → 6.27.0

---

Use of Insufficiently Random Values in undici

CVE-2025-22150 / GHSA-c76h-2ccp-4975

More information

Details

Impact

Undici fetch() uses Math.random() to choose the boundary for a multipart/form-data request. It is known that the output of Math.random() can be predicted if several of its generated values are known.

If there is a mechanism in an app that sends multipart requests to an attacker-controlled website, they can use this to leak the necessary values. Therefore, An attacker can tamper with the requests going to the backend APIs if certain conditions are met.

Patches

This is fixed in 5.28.5; 6.21.1; 7.2.3.

Workarounds

Do not issue multipart requests to attacker controlled servers.

References

• https://hackerone.com/reports/2913312
• https://blog.securityevaluators.com/hacking-the-javascript-lottery-80cc437e3b7f

Severity

• CVSS Score: 6.8 / 10 (Medium)
• Vector String: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N

References

• https://github.com/nodejs/undici/security/advisories/GHSA-c76h-2ccp-4975
• https://nvd.nist.gov/vuln/detail/CVE-2025-22150
• https://github.com/nodejs/undici/commit/711e20772764c29f6622ddc937c63b6eefdf07d0
• https://github.com/nodejs/undici/commit/c2d78cd19fe4f4c621424491e26ce299e65e934a
• https://github.com/nodejs/undici/commit/c3acc6050b781b827d80c86cbbab34f14458d385
• https://hackerone.com/reports/2913312
• https://blog.securityevaluators.com/hacking-the-javascript-lottery-80cc437e3b7f
• https://github.com/nodejs/undici/blob/8b06b8250907d92fead664b3368f1d2aa27c1f35/lib/web/fetch/body.js#L113
• https://github.com/advisories/GHSA-c76h-2ccp-4975

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

---

undici Denial of Service attack via bad certificate data

CVE-2025-47279 / GHSA-cxrh-j4jr-qwg3

More information

Details

Impact

Applications that use undici to implement a webhook-like system are vulnerable. If the attacker set up a server with an invalid certificate, and they can force the application to call the webhook repeatedly, then they can cause a memory leak.

Patches

This has been patched in https://github.com/nodejs/undici/pull/4088.

Workarounds

If a webhook fails, avoid keep calling it repeatedly.

References

Reported as: https://github.com/nodejs/undici/issues/3895

Severity

• CVSS Score: 3.1 / 10 (Low)
• Vector String: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L

References

• https://github.com/nodejs/undici/security/advisories/GHSA-cxrh-j4jr-qwg3
• https://github.com/nodejs/undici/issues/3895
• https://github.com/nodejs/undici/pull/4088
• https://nvd.nist.gov/vuln/detail/CVE-2025-47279
• https://github.com/nodejs/undici/commit/f317618ec28753a4218beccea048bcf89c36db25
• https://github.com/advisories/GHSA-cxrh-j4jr-qwg3

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

---

Undici has an unbounded decompression chain in HTTP responses on Node.js Fetch API via Content-Encoding leads to resource exhaustion

CVE-2026-22036 / GHSA-g9mf-h72j-4rw9

More information

Details

Impact

The fetch() API supports chained HTTP encoding algorithms for response content according to RFC 9110 (e.g., Content-Encoding: gzip, br). This is also supported by the undici decompress interceptor.

However, the number of links in the decompression chain is unbounded and the default maxHeaderSize allows a malicious server to insert thousands compression steps leading to high CPU usage and excessive memory allocation.

Patches

Upgrade to 7.18.2 or 6.23.0.

Workarounds

It is possible to apply an undici interceptor and filter long Content-Encoding sequences manually.

References

• https://hackerone.com/reports/3456148
• GHSA-gm62-xv2j-4w53
• https://curl.se/docs/CVE-2022-32206.html

Severity

• CVSS Score: 5.9 / 10 (Medium)
• Vector String: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

References

• https://github.com/nodejs/undici/security/advisories/GHSA-g9mf-h72j-4rw9
• https://github.com/nodejs/undici/commit/b04e3cbb569c1596f86c108e9b52c79d8475dcb3
• https://nvd.nist.gov/vuln/detail/CVE-2026-22036
• https://github.com/advisories/GHSA-g9mf-h72j-4rw9

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

---

Undici: Malicious WebSocket 64-bit length overflows parser and crashes the client

CVE-2026-1528 / GHSA-f269-vfmq-vjvj

More information

Details

Impact

A server can reply with a WebSocket frame using the 64-bit length form and an extremely large length. undici's ByteParser overflows internal math, ends up in an invalid state, and throws a fatal TypeError that terminates the process.

Patches

Patched in the undici version v7.24.0 and v6.24.0. Users should upgrade to this version or later.

Workarounds

There are no workarounds.

Severity

• CVSS Score: 7.5 / 10 (High)
• Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

• https://github.com/nodejs/undici/security/advisories/GHSA-f269-vfmq-vjvj
• https://nvd.nist.gov/vuln/detail/CVE-2026-1528
• https://hackerone.com/reports/3537648
• https://cna.openjsf.org/security-advisories.html
• https://github.com/advisories/GHSA-f269-vfmq-vjvj

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

---

Undici has an HTTP Request/Response Smuggling issue

CVE-2026-1525 / GHSA-2mjp-6q6p-2qxm

More information

Details

Impact

Undici allows duplicate HTTP Content-Length headers when they are provided in an array with case-variant names (e.g., Content-Length and content-length). This produces malformed HTTP/1.1 requests with multiple conflicting Content-Length values on the wire.

Who is impacted:

• Applications using undici.request(), undici.Client, or similar low-level APIs with headers passed as flat arrays
• Applications that accept user-controlled header names without case-normalization

Potential consequences:

• Denial of Service: Strict HTTP parsers (proxies, servers) will reject requests with duplicate Content-Length headers (400 Bad Request)
• HTTP Request Smuggling: In deployments where an intermediary and backend interpret duplicate headers inconsistently (e.g., one uses the first value, the other uses the last), this can enable request smuggling attacks leading to ACL bypass, cache poisoning, or credential hijacking

Patches

Patched in the undici version v7.24.0 and v6.24.0. Users should upgrade to this version or later.

Workarounds

If upgrading is not immediately possible:

1. Validate header names: Ensure no duplicate Content-Length headers (case-insensitive) are present before passing headers to undici
2. Use object format: Pass headers as a plain object ({ 'content-length': '123' }) rather than an array, which naturally deduplicates by key
3. Sanitize user input: If headers originate from user input, normalize header names to lowercase and reject duplicates

Severity

• CVSS Score: 6.5 / 10 (Medium)
• Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

References

• https://github.com/nodejs/undici/security/advisories/GHSA-2mjp-6q6p-2qxm
• https://nvd.nist.gov/vuln/detail/CVE-2026-1525
• https://hackerone.com/reports/3556037
• https://cna.openjsf.org/security-advisories.html
• https://cwe.mitre.org/data/definitions/444.html
• https://www.rfc-editor.org/rfc/rfc9110.html#section-8.6
• https://github.com/advisories/GHSA-2mjp-6q6p-2qxm

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

---

Undici has Unhandled Exception in WebSocket Client Due to Invalid server_max_window_bits Validation

CVE-2026-2229 / GHSA-v9p9-hfj2-hcw8

More information

Details

Impact

The undici WebSocket client is vulnerable to a denial-of-service attack due to improper validation of the server_max_window_bits parameter in the permessage-deflate extension. When a WebSocket client connects to a server, it automatically advertises support for permessage-deflate compression. A malicious server can respond with an out-of-range server_max_window_bits value (outside zlib's valid range of 8-15). When the server subsequently sends a compressed frame, the client attempts to create a zlib InflateRaw instance with the invalid windowBits value, causing a synchronous RangeError exception that is not caught, resulting in immediate process termination.

The vulnerability exists because:

1. The isValidClientWindowBits() function only validates that the value contains ASCII digits, not that it falls within the valid range 8-15
2. The createInflateRaw() call is not wrapped in a try-catch block
3. The resulting exception propagates up through the call stack and crashes the Node.js process

Patches

Has the problem been patched? What versions should users upgrade to?

Workarounds

Is there a way for users to fix or remediate the vulnerability without upgrading?

Severity

• CVSS Score: 7.5 / 10 (High)
• Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

• https://github.com/nodejs/undici/security/advisories/GHSA-v9p9-hfj2-hcw8
• https://nvd.nist.gov/vuln/detail/CVE-2026-2229
• https://hackerone.com/reports/3487486
• https://cna.openjsf.org/security-advisories.html
• https://datatracker.ietf.org/doc/html/rfc7692
• https://nodejs.org/api/zlib.html#class-zlibinflateraw
• https://github.com/advisories/GHSA-v9p9-hfj2-hcw8

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

---

Undici has Unbounded Memory Consumption in WebSocket permessage-deflate Decompression

CVE-2026-1526 / GHSA-vrm6-8vpv-qv8q

More information

Details

Description

The undici WebSocket client is vulnerable to a denial-of-service attack via unbounded memory consumption during permessage-deflate decompression. When a WebSocket connection negotiates the permessage-deflate extension, the client decompresses incoming compressed frames without enforcing any limit on the decompressed data size. A malicious WebSocket server can send a small compressed frame (a "decompression bomb") that expands to an extremely large size in memory, causing the Node.js process to exhaust available memory and crash or become unresponsive.

The vulnerability exists in the PerMessageDeflate.decompress() method, which accumulates all decompressed chunks in memory and concatenates them into a single Buffer without checking whether the total size exceeds a safe threshold.

Impact

• Remote denial of service against any Node.js application using undici's WebSocket client
• A single compressed WebSocket frame of ~6 MB can decompress to ~1 GB or more
• Memory exhaustion occurs in native/external memory, bypassing V8 heap limits
• No application-level mitigation is possible as decompression occurs before message delivery

Patches

Users should upgrade to fixed versions.

Workarounds

No workaround are possible.

Severity

• CVSS Score: 7.5 / 10 (High)
• Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

• https://github.com/nodejs/undici/security/advisories/GHSA-vrm6-8vpv-qv8q
• https://nvd.nist.gov/vuln/detail/CVE-2026-1526
• https://hackerone.com/reports/3481206
• https://cna.openjsf.org/security-advisories.html
• https://datatracker.ietf.org/doc/html/rfc7692
• https://owasp.org/www-community/attacks/Denial_of_Service
• https://github.com/advisories/GHSA-vrm6-8vpv-qv8q

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

---

Undici has CRLF Injection in undici via upgrade option

CVE-2026-1527 / GHSA-4992-7rv2-5pvq

More information

Details

Impact

When an application passes user-controlled input to the upgrade option of client.request(), an attacker can inject CRLF sequences (\r\n) to:

1. Inject arbitrary HTTP headers
2. Terminate the HTTP request prematurely and smuggle raw data to non-HTTP services (Redis, Memcached, Elasticsearch)

The vulnerability exists because undici writes the upgrade value directly to the socket without validating for invalid header characters:

// lib/dispatcher/client-h1.js:1121
if (upgrade) {
  header += `connection: upgrade\r\nupgrade: ${upgrade}\r\n`
}

Patches

Patched in the undici version v7.24.0 and v6.24.0. Users should upgrade to this version or later.

Workarounds

Sanitize the upgrade option string before passing to undici:

function sanitizeUpgrade(value) {
  if (/[\r\n]/.test(value)) {
    throw new Error('Invalid upgrade value')
  }
  return value
}

client.request({
  upgrade: sanitizeUpgrade(userInput)
})

Severity

• CVSS Score: 4.6 / 10 (Medium)
• Vector String: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N

References

• https://github.com/nodejs/undici/security/advisories/GHSA-4992-7rv2-5pvq
• https://nvd.nist.gov/vuln/detail/CVE-2026-1527
• https://hackerone.com/reports/3487198
• https://cna.openjsf.org/security-advisories.html
• https://github.com/advisories/GHSA-4992-7rv2-5pvq

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

---

undici WebSocket client vulnerable to denial of service via fragment count bypass

CVE-2026-12151 / GHSA-vxpw-j846-p89q

More information

Details

Impact

The undici WebSocket client enforces maxPayloadSize on the cumulative byte count of fragments in a message but does not enforce a limit on the number of fragments. A malicious WebSocket server can stream many small or empty continuation frames that each pass per-frame and cumulative-size validation, collectively causing unbounded memory growth in the client process. The result is memory exhaustion and a denial of service.

Affected applications are those using the undici WebSocket client (new WebSocket(...)) or the WebSocketStream API that can be induced to connect to an attacker-controlled or compromised WebSocket endpoint.

All releases starting at undici 6.17.0 are affected.

Patches

Upgrade to undici v6.27.0, v7.28.0 or v8.5.0.

Workarounds

No workaround is available. The fix must be applied through an upgrade.

Severity

• CVSS Score: 7.5 / 10 (High)
• Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

• https://github.com/nodejs/undici/security/advisories/GHSA-vxpw-j846-p89q
• https://nvd.nist.gov/vuln/detail/CVE-2026-12151
• https://cna.openjsf.org/security-advisories.html
• https://github.com/advisories/GHSA-vxpw-j846-p89q

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

---

undici vulnerable to HTTP response queue poisoning via keep-alive socket reuse

CVE-2026-6733 / GHSA-35p6-xmwp-9g52

More information

Details

Impact

Undici's HTTP/1.1 client is vulnerable to response queue poisoning on reused keep-alive sockets. An attacker-controlled upstream server can inject an unsolicited HTTP/1.1 response onto an idle socket after a request completes. When the client dispatches the next request on that socket, it associates the injected response with the new request, causing responses to be delivered to the wrong requests.

This requires an attacker-controlled or compromised upstream HTTP/1.1 server and keep-alive connection reuse.

Patches

Upgrade to undici v6.27.0, v7.28.0 or v8.5.0.

Workarounds

Disable keep-alive connection reuse by setting keepAliveTimeout: 0 on the Client or Pool.

Severity

• CVSS Score: 3.7 / 10 (Low)
• Vector String: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

References

• https://github.com/nodejs/undici/security/advisories/GHSA-35p6-xmwp-9g52
• https://nvd.nist.gov/vuln/detail/CVE-2026-6733
• https://hackerone.com/reports/3582376
• https://cna.openjsf.org/security-advisories.html
• https://github.com/advisories/GHSA-35p6-xmwp-9g52

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

---

undici vulnerable to HTTP header injection via Set-Cookie percent-decoding

CVE-2026-9679 / GHSA-p88m-4jfj-68fv

More information

Details

Impact

undici's cookie parser in parseSetCookie percent-decodes cookie values via qsUnescape, turning encoded sequences like %0D%0A, %00, %3B, and %3D into their literal byte equivalents. RFC 6265 §5.4 does not specify any decoding and browsers do not decode either.

Applications that parse a Set-Cookie header and then forward the parsed value into a response header (proxies, middleware, SSR frameworks) become vulnerable to HTTP response header injection: an attacker-controlled upstream can inject arbitrary Set-Cookie, Location, or Cache-Control headers into the application's downstream response, enabling session fixation, open redirect, or cache poisoning.

Affected applications are those that use undici's cookie parsing (parseSetCookie, parseCookie, getSetCookies) and forward the parsed cookie value into a response header.

This was introduced in undici 7.0.0 via #​3789.

Patches

Upgrade to undici v6.27.0, v7.28.0 or v8.5.0.

Workarounds

If upgrade is not immediately possible, do not forward values returned by parseSetCookie/parseCookie/getSetCookies directly into response headers; sanitize the value first to strip or reject CR, LF, NUL, ;, and = bytes.

Severity

• CVSS Score: 5.9 / 10 (Medium)
• Vector String: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

References

• https://github.com/nodejs/undici/security/advisories/GHSA-p88m-4jfj-68fv
• https://nvd.nist.gov/vuln/detail/CVE-2026-9679
• https://cna.openjsf.org/security-advisories.html
• https://github.com/advisories/GHSA-p88m-4jfj-68fv

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

---

undici vulnerable to Set-Cookie SameSite attribute downgrade via permissive substring matching

CVE-2026-11525 / GHSA-g8m3-5g58-fq7m

More information

Details

Impact

When undici parses a Set-Cookie header, it accepts any SameSite attribute value that contains Strict, Lax, or None as a substring, rather than the case-insensitive exact match specified by RFC 6265. Non-spec values are silently mapped to one of the three standard tokens:

• SameSite=NoneOfYourBusiness is parsed as None, the most permissive setting.
• SameSite=StrictLax is parsed as Lax, a downgrade from Strict.

Affected applications are those that consume Set-Cookie headers from server responses (for example via undici's fetch or proxy code paths) and then forward or rely on the parsed sameSite attribute. A malicious or non-compliant server can coerce the consumer's view of a cookie's SameSite policy to a weaker value, silently degrading the SameSite enforcement the cookie is supposed to provide.

This was introduced in undici 5.15.0 when the cookies feature was added.

Patches

Upgrade to undici v6.27.0, v7.28.0 or v8.5.0.

Workarounds

After parsing a Set-Cookie header, validate that the resulting sameSite attribute is one of 'Strict', 'Lax', or 'None' (exact, case-insensitive) before forwarding or relying on it.

Severity

• CVSS Score: 3.7 / 10 (Low)
• Vector String: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

References

• https://github.com/nodejs/undici/security/advisories/GHSA-g8m3-5g58-fq7m
• https://nvd.nist.gov/vuln/detail/CVE-2026-11525
• https://cna.openjsf.org/security-advisories.html
• https://github.com/advisories/GHSA-g8m3-5g58-fq7m

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

---

Release Notes

nodejs/undici (undici)

v6.27.0

Compare Source

⚠️ Security Release

This release line addresses 4 security advisories.

Action required: Upgrade to undici 6.27.0 or later.

npm install undici@^6.27.0

Note on patched version: the v6 fixes shipped in v6.27.0, not 6.26.0
— v6.26.0 contains only the chunked-EOF fix (#​5308) and the version bump, none
of the security fixes below.

The v6 line is not affected by the SOCKS5 advisories (GHSA-vmh5-mc38-953g,
GHSA-hm92-r4w5-c3mj), the shared-cache disclosure (GHSA-pr7r-676h-xcf6), or the
8.x-only WebSocket regression (GHSA-38rv-x7px-6hhq).

Summary

Advisory	CVE	Severity (CVSS)	Fixed in	Fix commit
GHSA-vxpw-j846-p89q	CVE-2026-12151	High (7.5)	6.27.0	b7f252e7
GHSA-p88m-4jfj-68fv	CVE-2026-9679	Moderate (5.9)	6.27.0	25efa447
GHSA-g8m3-5g58-fq7m	CVE-2026-11525	Low (3.7)	6.27.0	25efa447
GHSA-35p6-xmwp-9g52	CVE-2026-6733	Low (3.7)	6.27.0	f4c31d60

---

High severity

WebSocket DoS via fragment count bypass — CVE-2026-12151

GHSA-vxpw-j846-p89q · CWE-400, CWE-770
Fix: b7f252e7 Backport WebSocket maxPayloadSize fixes (#​5423, backported to v6 in #​5428)

A malicious WebSocket server can stream a large number of small or empty
continuation frames. Undici enforced a limit on cumulative payload size but did
not limit the number of fragments per message, leading to unbounded memory
growth and denial of service. All releases from 6.17.0 onward are affected.

• Affected: applications using new WebSocket(...) or WebSocketStream
  against untrusted endpoints.
• Workaround: none — upgrade is required.

---

Moderate severity

HTTP header injection via Set-Cookie percent-decoding — CVE-2026-9679

GHSA-p88m-4jfj-68fv · CWE-93
Fix: 25efa447 fix(cookies): preserve values and parse SameSite strictly

parseSetCookie applied percent-decoding to cookie values, turning encoded
sequences like %0D%0A and %00 into literal bytes, contrary to RFC 6265 §5.4
and browser behavior. Applications forwarding parsed Set-Cookie values into
response headers were exposed to header injection, enabling session fixation,
open redirects, and cache poisoning.

• Workaround: sanitize values before forwarding — strip or reject CR, LF,
  NUL, ;, and =.

---

Low severity

Set-Cookie SameSite attribute downgrade — CVE-2026-11525

GHSA-g8m3-5g58-fq7m · CWE-183
Fix: 25efa447 fix(cookies): preserve values and parse SameSite strictly

The cookie parser accepted SameSite values containing Strict, Lax, or
None as substrings rather than requiring exact matches per RFC 6265. Values
like SameSite=NoneOfYourBusiness parsed as None, and SameSite=StrictLax
parsed as Lax, silently weakening cookie security policies for apps that
forward parsed attributes.

HTTP response queue poisoning via keep-alive socket reuse — CVE-2026-6733

GHSA-35p6-xmwp-9g52 · CWE-367 (TOCTOU race condition)
Fix: f4c31d60 fix: guard idle socket validation to skip fresh sockets (#​5400)

An attacker controlling an upstream HTTP/1.1 server could inject unsolicited
responses onto idle keep-alive sockets. On socket reuse, the injected response
was associated with a new request, delivering responses to the wrong requests.

• Requirements: attacker-controlled/compromised upstream and active
  keep-alive reuse.
• Workaround: disable keep-alive reuse with keepAliveTimeout: 0 on the
  Client or Pool.

---

Release contents & deliberate backports

v6.27.0 is a security-only release — every change in it is one of the fixes
above, backported to the v6.x maintenance line on purpose:

• #5428 — backport of the WebSocket maxPayloadSize fragment-count / cumulative-size limits to v6.x (CVE-2026-12151; this is the v6 counterpart of the v7 backport #​5423).
• #5400 — idle-socket-validation fix for the queue-poisoning issue (CVE-2026-6733).

The cookie fix (25efa447,
covering both CVE-2026-9679 and CVE-2026-11525) was applied directly to the v6.x
branch. Full changelog:
v6.26.0...v6.27.0.

---

Credits

Per-advisory credits (as recorded in each GHSA):

• CVE-2026-12151 — reported by @​lpinca & @​Nadav0077; reviewed by @​UlisesGascon.
• CVE-2026-9679 — reported by @​tndud042713; fixed by @​mcollina; reviewed by @​KhafraDev & @​UlisesGascon.
• CVE-2026-11525 — fixed by @​mcollina; reviewed by @​UlisesGascon.
• CVE-2026-6733 — fixed by @​mcollina; verified by @​UlisesGascon.

v6.26.0

Compare Source

What's Changed

• fix: validate EOF for chunked h1 responses by @​mcollina in #​5308

Full Changelog: nodejs/undici@v6.25.0...v6.26.0

v6.25.0

Compare Source

What's Changed

Full Changelog: nodejs/undici@v6.24.1...v6.25.0

v6.24.1

Compare Source

Full Changelog: nodejs/undici@v6.24.0...v6.24.1

v6.24.0

Compare Source

Undici v6.24.0 Security Release Notes (LTS)

This release backports fixes for security vulnerabilities affecting the v6 line.

Upgrade guidance

All users on v6 should upgrade to v6.24.0 or later.

Fixed advisories

• GHSA-2mjp-6q6p-2qxm / CVE-2026-1525 (Medium)
  Inconsistent interpretation of HTTP requests (request/response smuggling class issue).

• GHSA-f269-vfmq-vjvj / CVE-2026-1528 (High)
  Malicious WebSocket 64-bit frame length handling could crash the client.

• GHSA-4992-7rv2-5pvq / CVE-2026-1527 (Medium)
  CRLF injection via the upgrade option.

• GHSA-v9p9-hfj2-hcw8 / CVE-2026-2229 (High)
  Unhandled exception from invalid server_max_window_bits in WebSocket permessage-deflate negotiation.

• GHSA-vrm6-8vpv-qv8q / CVE-2026-1526 (High)
  Unbounded memory consumption in WebSocket permessage-deflate decompression.

Not applicable to v6

• GHSA-phc3-fgpg-7m6h / CVE-2026-2581 affects >= 7.17.0 < 7.24.0 only.

Affected and patched ranges (v6)

• CVE-2026-1525: affected < 6.24.0, patched 6.24.0
• CVE-2026-1528: affected >= 6.0.0 < 6.24.0, patched 6.24.0
• CVE-2026-1527: affected < 6.24.0, patched 6.24.0
• CVE-2026-2229: affected < 6.24.0, patched 6.24.0
• CVE-2026-1526: affected < 6.24.0, patched 6.24.0

References

• GitHub Security Advisories: https://github.com/nodejs/undici/security/advisories
• NVD CVE-2026-1525: https://nvd.nist.gov/vuln/detail/CVE-2026-1525
• NVD CVE-2026-1528: https://nvd.nist.gov/vuln/detail/CVE-2026-1528
• NVD CVE-2026-1527: https://nvd.nist.gov/vuln/detail/CVE-2026-1527
• NVD CVE-2026-2229: https://nvd.nist.gov/vuln/detail/CVE-2026-2229
• NVD CVE-2026-1526: https://nvd.nist.gov/vuln/detail/CVE-2026-1526

v6.23.0

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⚠️ Security Release

This fixes GHSA-g9mf-h72j-4rw9 and CVE-2026-22036.

Full Changelog: nodejs/undici@v6.22.0...v6.23.0

v6.22.0

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What's Changed

• fix: fix wrong stream canceled up after cloning (v6) by @​snyamathi in #​4414
• [Backport v6.x] fix: fix EnvHttpProxyAgent for the Node.js bundle by @​github-actions[bot] in #​4432
• feat(ProxyAgent): match Curl behavior in HTTP->HTTP Proxy connections (#​4180) by @​metcoder95 in #​4433
• feat(ProxyAgent) improve Curl-y behavior in HTTP->HTTP Proxy connections (#​4180) (#​4340) by @​metcoder95 in #​4445
• Backport 4472 to v6.x by @​Uzlopak in #​4480

Full Changelog: nodejs/undici@v6.21.3...v6.22.0

v6.21.3

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What's Changed

• [Backport v6.x] append crlf to formdata body by @​github-actions in #​4210

Full Changelog: nodejs/undici@v6.21.2...v6.21.3

v6.21.2

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What's Changed

• fix(types): add missing DNS interceptor by @​slagiewka in #​4024
• [v6.x] fix wpts on windows by @​mcollina in #​4093
• Removed clients with unrecoverable errors from the Pool #​4088

New Contributors

• @​slagiewka made their first contribution in #​4024

Full Changelog: nodejs/undici@v6.21.1...v6.21.2

v6.21.1

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⚠️ Security Release ⚠️

Fixes CVE CVE-2025-22150 GHSA-c76h-2ccp-4975 (embargoed until 22-01-2025).

What's Changed

• fix(#​3736): back-port 183f8e9 to v6.x by @​ggoodman in #​3855
• fix(#​3817): send servername for SNI on TLS (#​3821) [backport] by @​metcoder95 in #​3864
• fix: sending formdata bodies with http2 (#​3863) [backport] by @​metcoder95 in #​3866
• [Backport v6.x] fix: Fixed the issue that there is no running request when http2 goaway by @​github-actions in #​3877
• types: [backport] Update return type of RetryCallback (#​3851) by @​metcoder95 in #​3876

Full Changelog: nodejs/undici@v6.21.0...v6.21.1

v6.21.0

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What's Changed

• [Backport v6.x] web: mark as uncloneable when possible (#​3709) by @​jazelly in #​3744
• [Backport v6.x] fetch: fix content-encoding order by @​github-actions in #​3764
• [Backport v6.x] fix: handle undefined deref() of WeakRef(socket) by @​github-actions in #​3822
• [Backport v6.x] fix: range end is zero-indexed by @​github-actions in #​3827

Full Changelog: nodejs/undici@v6.20.1...v6.21.0

v6.20.1

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What's Changed

• [Backport v6.x] jsdoc: add jsdoc to lib/web/fetch/constants.js by @​github-actions in #​3710
• [Backport v6.x] feat: implement BodyReadable.bytes by @​github-actions in #​3711
• fix: add more expectsPayload methods by @​ronag in #​3715
• [Backport v6.x] chore(H2): onboard H2 into Undici queueing system (#​3707) by @​Uzlopak in #​3724
• [Backport v6.x] fix: PoolBase kClose and kDestroy should await and not return the Promise by @​github-actions in #​3723
• [Backport v6.x] fix: extract noop everywhere by @​Uzlopak in #​3727

Full Changelog: nodejs/undici@v6.20.0...v6.20.1

v6.20.0

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What's Changed

• Remove patched dom types (v6.x branch) by @​eXhumer in #​3531
• docs(Backport v6.x): Fix signature of RetryHandler by @​github-actions in #​3594
• deps(dev): update @​types/node by @​metcoder95 in #​3618
• fix: throw on retry when payload is consume by downstream by @​github-actions in #​3596
• feat(Backport v6.x): move throwOnError to interceptor by @​github-actions in #​3595
• [Backport v6.x] fix: reduce memory usage in client-h1 by @​github-actions in #​3672
• [Backport v6.x] fix: refactor fast timers, fix UND_ERR_CONNECT_TIMEOUT on event loop blocking by @​github-actions in #​3673
• [Backport v6.x] fix: run asserts first if possible by @​github-actions in #​3674
• [Backport v6.x] fix: use fasttimers for all connection timeouts by @​github-actions in #​3675
• [Backport v6.x] ci: less flaky test/request-timeout.js test by @​github-actions in #​3678
• [Backport v6.x] test: less flaky timers acceptance test, rework fast timer tests to pass them faster by @​github-actions in #​3679
• [Backport v6.x] ignore leading and trailing crlfs in formdata body by @​github-actions in #​3681
• [Backport v6.x] mock: fix mocking of Uint8Array and ArrayBuffers as provided mock-responses by @​github-actions in #​3689
• [Backport v6.x] handle body errors by @​Uzlopak in #​3700

Full Changelog: nodejs/undici@v6.19.8...v6.20.0

v6.19.8

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Full Changelog: nodejs/undici@v6.19.7...v6.19.8

v6.19.7

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Full Changelog: nodejs/undici@v6.19.6...v6.19.7

v6.19.6

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Full Changelog: nodejs/undici@v6.19.5...v6.19.6

v6.19.5

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Full Changelog: nodejs/undici@v6.19.4...v6.19.5

v6.19.4

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Full Changelog: nodejs/undici@v6.19.3...v6.19.4

v6.19.3

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Full Changelog: nodejs/undici@v6.19.2...v6.19.3

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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.60%. Comparing base (0edc5dc) to head (77f1cb3).
⚠️ Report is 26 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #234      +/-   ##
==========================================
- Coverage   98.65%   96.60%   -2.06%     
==========================================
  Files          51       48       -3     
  Lines        1933     1943      +10     
  Branches      513      489      -24     
==========================================
- Hits         1907     1877      -30     
- Misses         23       59      +36     
- Partials        3        7       +4     

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