CVE-2026-98994 statmount: read the parent of an unmounted mount under mount_lock
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-98994?
CVE-2026-98994 is a vulnerability in Linux, published on 23 Oct 2026.
Official description
In the Linux kernel, the following vulnerability has been resolved:
statmount: read the parent of an unmounted mount under mount_lock
statmount_mnt_basic() reads the ids of the parent through m->mnt_parent with namespace_sem held for reading. That's fine for a mount that is in a namespace. Everything above it is pinned by that namespace.
STATMOUNT_BY_FD also accepts a file descriptor on a mount that has been unmounted on purpose and that only the file descriptor keeps alive. If that mount stayed attached to its parent when it was unmounted the parent is unmounted as well and nothing pins it for the child.
The final mntput() unmounts the children under mount_lock alone and frees the parent afterwards. Concurrently, statmount_mnt_basic() reads m->mnt_parent twice while that can happen and can easily dereference a mount that's already gone.
Read the parent of an unmounted mount under mount_lock. The parent can't be put while it is held and both ids come from the same mount. A mounted mount's parent is pinned by the namespace and a mount can't leave its namespace while namespace_sem is held, so the common case takes no global lock.
Which versions are affected by CVE-2026-98994?
How do I fix CVE-2026-98994?
Upgrade to a fixed version.
Is CVE-2026-98994 being exploited?
There is no known exploitation of CVE-2026-98994 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-98994, GHSA-2fr8-4rp8-wvj2, UBUNTU-CVE-2026-98994.