CVE-2026-52909
HighCVSS 7.8Exploitation Probability (EPSS)
Low risk2th percentile - higher than 2% of all known CVEs
Summary
In the Linux kernel, a vulnerability was found in the ip6_vti driver where the fallback device (ip6_vti0) does not have the netns_immutable flag set. Other similar tunnel drivers (e.g., ip6_tunnel, sit) correctly set this flag to prevent the device from being moved to another network namespace.
Risk Assessment
The missing netns_immutable flag could allow the fallback device to be moved to another network namespace, potentially breaking network isolation and leading to data leakage between containers or virtual machines.
Recommendation
Immediately update the Linux kernel to a version that includes the fix that sets the netns_immutable flag on the ip6_vti0 fallback device.
Original NVD description (English source)
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.