DEBIAN-CVE-2026-11525

Advisory lineage Upstream: 1 Downstream: 0
Upstream
CVE-2026-11525
Published: 17 Jun 2026, 18:17
Last modified:28 Jun 2026, 05:00

Vulnerability Summary

Overall Risk (default)
low
15/100
CVSS Score
3.7 LOW
3.1 (osv_debian)
EPSS Score
No data
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

17 Jun 2026, 18:17
Published
Vulnerability first disclosed
28 Jun 2026, 05:00
Last Modified
Vulnerability information updated

Description

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.

CVSS Metrics

  • v3.1•LOW•Score: 3.7CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected Systems

  • debian•node-undici

    all | all | all | < 8.5.0+dfsg+~cs3.2.0-1

References (1)