CVE-2026-16729 (MEDIUM): 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-2026-16729	MEDIUM	undici	6.26.0	6.28.0, 7.29.0, 8.9.0	2026-07-29T17:16:51.123Z	2026-08-04T10:19:08.862184301Z

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Affected Docker Images

Image Name	SHA
public.ecr.aws/lambda/nodejs:latest	public.ecr.aws/lambda/nodejs@sha256:fe69820efd000f4a6a34af1fc61ad476e8266f14fa8ebde7688564efba67a2df
public.ecr.aws/lambda/nodejs:24	public.ecr.aws/lambda/nodejs@sha256:fe69820efd000f4a6a34af1fc61ad476e8266f14fa8ebde7688564efba67a2df

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Description

undici's setCookie function does not fully sanitize cookie attributes. In undici before 6.28.0, from 7.0.0 up to before 7.29.0, and from 8.0.0 up to before 8.9.0, a domain value is not checked for semicolons and entries in the unparsed array are not sanitized, so attacker-influenced input can inject additional cookie attributes. For example, a domain value containing a semicolon can append attributes such as SameSite, and an unparsed entry can inject attributes such as HttpOnly, without the caller setting them. Applications that pass user-controlled input to these fields, such as multi-tenant or reverse-proxy servers that scope session cookies to a tenant-supplied domain, can have SameSite CSRF protections bypassed, or the Secure, HttpOnly, and SameSite attributes forced, stripped, or overridden. The issue is fixed in undici 6.28.0, 7.29.0, and 8.9.0.

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Remediation Steps

• Update the affected package undici from version 6.26.0 to 6.28.0, 7.29.0, 8.9.0.

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.