CVE-2026-11525 (LOW): detected in Lambda Docker Images.

[the-lambda-watchdog]

CVE Details

CVE ID	Severity	Affected Package	Installed Version	Fixed Version	Date Published	Date of Scan
CVE-2026-11525	LOW	undici	6.25.0	6.27.0, 7.28.0, 8.5.0	2026-06-17T18:17:35.097Z	2026-06-24T10:18:20.293117067Z

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Affected Docker Images

Image Name	SHA
public.ecr.aws/lambda/nodejs:24	public.ecr.aws/lambda/nodejs@sha256:904f7a98db07d37b59bf7edd90ed97bbba1cb574fd86db462205c68cfc55486c

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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.

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Remediation Steps

• Update the affected package undici from version 6.25.0 to 6.27.0, 7.28.0, 8.5.0.

About this issue

• This issue may not contain all the information about the CVE nor the images it affects.
• This issue will not be updated with new information and the list of affected images may have changed since the creation of this issue.
• For more, visit Lambda Watchdog.
• This issue was created automatically by Lambda Watchdog.