CVE-2026-52909

Name	CVE-2026-52909
Description	In the Linux kernel, the following vulnerability has been resolved: ip6_vti: set netns_immutable on the fallback device. john1988 and Noam Rathaus reported that vti6_init_net() does not set the netns_immutable flag on the per-netns fallback tunnel device (ip6_vti0). Other similar tunnel drivers (like ip6_tunnel, sit, ip6_gre, and ip_tunnel) correctly set this flag during their fallback device initialization to prevent them from being moved to another network namespace.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
References	DSA-6355-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
linux (PTS)	bullseye	5.10.223-1	vulnerable
	bullseye (security)	5.10.257-1	vulnerable
	bookworm	6.1.170-3	vulnerable
	bookworm (security)	6.1.174-1	vulnerable
	trixie	6.12.86-1	vulnerable
	trixie (security)	6.12.94-1	fixed
	forky	7.0.12-2	vulnerable
	sid	7.0.13-1	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
linux	source	trixie	6.12.94-1		DSA-6355-1
linux	source	(unstable)	7.0.13-1

https://git.kernel.org/linus/d289d5307762d1838aaece22c6b6fcad9e8865f9 (7.1)