CVE-2026-98543 bpf: fs/xattr: don't assume the inode is locked in path_unlink/path_rmdir
A race condition in Linux kernel BPF LSM hooks allows local attackers to modify file extended attributes without proper locking, potentially leading to privilege escalation.
- 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-2026-98543?
CVE-2026-98543 is a high-severity vulnerability in Linux, published on 18 Oct 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:
bpf: fs/xattr: don't assume the inode is locked in path_unlink/path_rmdir
bpf_lsm_has_d_inode_locked() makes the verifier rewrite bpf_[set|remove]_dentry_xattr() to the _locked variants, which assume that the caller already holds the inode's i_rwsem. The path_unlink and path_rmdir hooks are listed, but security_path_unlink() and security_path_rmdir() run before vfs_unlink()/vfs_rmdir() take the victim inode's i_rwsem, so a sleepable BPF LSM program attached to either hook mutates the victim's xattrs without the lock held.
Drop the two path hooks from d_inode_locked_hooks so that the verifier keeps the locking bpf_[set|remove]_dentry_xattr() variants, which take the lock themselves.
Which versions are affected by CVE-2026-98543?
How do I fix CVE-2026-98543?
Apply the vendor's patch.
Is CVE-2026-98543 being exploited?
There is no known exploitation of CVE-2026-98543 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-98543, DEBIAN-CVE-2026-98543, GHSA-mhp5-jj6j-c7m7, UBUNTU-CVE-2026-98543.