Linux Kernel Vulnerability in IP GRE Tunneling Feature by Linux

CVE-2026-63829

What is CVE-2026-63829?

The Linux kernel had a vulnerability in the IP GRE (Generic Routing Encapsulation) tunneling feature that allowed unauthorized users to perform changelink operations on network devices. This occurred because the required administrative capability (CAP_NET_ADMIN) was only checked against the network namespace of the device, not the namespace of the tunnel itself, potentially enabling privilege escalation. The vulnerability has been addressed by ensuring that the proper permissions are checked within the relevant network namespace, preventing unauthorized modifications to live tunnel fields.

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