Linux Kernel Vulnerability in TUN/TAP Device Permissions

CVE-2026-99281

What is CVE-2026-99281?

A vulnerability in the Linux kernel related to TUN/TAP devices exists where ownerless devices can be attached without proper permissions. The initial design allowed for relaxed permissions on /dev/net/tun, leading to potential security risks since persistent devices without an owner were essentially accessible to any user. Recent developments aimed to mitigate these risks by enforcing that attachment to such devices now requires CAP_NET_ADMIN. Adjustments have been made to the permission model to ensure that stringent checks are applied, closing previously exploited loopholes. This highlights the ongoing need for vigilance in network device configurations and permission management.

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