PT-2026-51969 · Linux · Linux

Published 2026-06-24 · Updated 2026-06-24 · CVE-2026-53075

NVD

In the Linux kernel, the following vulnerability has been resolved:

ppp: require CAP NET ADMIN in target netns for unattached ioctls

/dev/ppp open is currently authorized against file->f cred->user ns, while unattached administrative ioctls operate on current->nsproxy->net ns.

As a result, a local unprivileged user can create a new user namespace with CLONE NEWUSER, gain CAP NET ADMIN only in that new user namespace, and still issue PPPIOCNEWUNIT, PPPIOCATTACH, or PPPIOCATTCHAN against an inherited network namespace.

Require CAP NET ADMIN in the user namespace that owns the target network namespace before handling unattached PPP administrative ioctls.

This preserves normal pppd operation in the network namespace it is actually privileged in, while rejecting the userns-only inherited-netns case.

Related Identifiers

CVE-2026-53075

Affected Products

Linux

References · 9

• https://nvd.nist.gov/vuln/detail/CVE-2026-53075 · Security Note
• https://git.kernel.org/stable/c/5013be175c7ffd8b39efbc3c9c4db5b10b85fea8 · Note
• https://git.kernel.org/stable/c/c9edd90c57ae23692fff6b049fdfa4572a9fd532 · Note
• https://git.kernel.org/stable/c/5080e188c914110034bbc569d5cfa2f06204681d · Note
• https://git.kernel.org/stable/c/3b2c2157dc2afc5c17cd7238afefca92f1ef330e · Note
• https://git.kernel.org/stable/c/1a8a51ce85075a56a743b6f142606dd2696a391c · Note
• https://git.kernel.org/stable/c/954745d0223e7caec917c0b2d1a889ff56fa6e54 · Note
• https://git.kernel.org/stable/c/2bb6379416fd19f44c3423a00bfd8626259f6067 · Note
• https://git.kernel.org/stable/c/67e901e28d177ac9a9bed76d69ce3471e704a89e · Note