Linux Kernel Vulnerability in IP6_VTI Fallback Device

CVE-2026-52909

What is CVE-2026-52909?

The Linux kernel has a vulnerability related to the initialization of the netns_immutable flag on the fallback device for the IP6_VTI tunnel. This oversight can lead to the fallback tunnel device, ip6_vti0, being moved to another network namespace, potentially exposing the system to unauthorized access and manipulation. Other similar tunnel drivers have been correctly handling this flag, but the absence of this precaution in the vti6_init_net() function raises significant security concerns for users relying on the IPv6 Virtual Tunnel Interface. Mitigating this issue is crucial to maintaining network integrity and security.

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