CVE-2026-53075 ppp: require CAP_NET_ADMIN in target netns for unattached ioctls
Local attackers can escalate privileges by exploiting PPP ioctl checks to bypass network namespace restrictions using user namespaces.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-53075?
CVE-2026-53075 is a high-severity vulnerability in Linux kernel, published on 24 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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.
Weakness: CWE-863
Which versions are affected by CVE-2026-53075?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-53075?
Apply the vendor's patch.
Is CVE-2026-53075 being exploited?
There is no known exploitation of CVE-2026-53075 in the wild and no public exploit code.
Public exploit code: 2 proofs of concept on GitHub.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-53075, DEBIAN-CVE-2026-53075, GHSA-v495-j4w2-68hc, ROOT-OS-DEBIAN-11-CVE-2026-53075, ROOT-OS-DEBIAN-12-CVE-2026-53075, ROOT-OS-UBUNTU-2204-CVE-2026-53075 and 2 more.