3.7

CVE-2026-11525

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

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. For example, SameSite=NoneOfYourBusiness is parsed as None (the most permissive setting), and 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 v6.26.0, 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.
Daten sind bereitgestellt durch National Vulnerability Database (NVD)
Nodejs ≫ Undici SwPlatformnode.js Version < 6.27.0
Nodejs ≫ Undici SwPlatformnode.js Version >= 7.0.0 < 7.28.0
Nodejs ≫ Undici SwPlatformnode.js Version >= 8.0.0 < 8.5.0
Zu dieser CVE wurde keine Warnung gefunden.
EPSS Metriken
Typ Quelle Score Percentile
EPSS FIRST.org 0.25% 0.158
CVSS Metriken
Quelle Base Score Exploit Score Impact Score Vector String
ce714d77-add3-4f53-aff5-83d477b104bb 3.7 2.2 1.4
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
CWE-183 Permissive List of Allowed Inputs

The product implements a protection mechanism that relies on a list of inputs (or properties of inputs) that are explicitly allowed by policy because the inputs are assumed to be safe, but the list is too permissive - that is, it allows an input that is unsafe, leading to resultant weaknesses.

https://cna.openjsf.org/security-advisories.html
Vendor Advisory
https://github.com/nodejs/undici/security/advisories/GHSA-g8m3-5g58-fq7m
Vendor Advisory
Mitigation