CVE-2026-74400 bpf: fix crash in bpf_[set|remove]_dentry_xattr for negative dentries
A local attacker can trigger a kernel crash via BPF kfuncs by passing negative dentries, causing a denial of service.
- 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-2026-74400?
CVE-2026-74400 is a vulnerability in Linux, published on 15 Aug 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: fix crash in bpf_[set|remove]_dentry_xattr for negative dentries
bpf_set_dentry_xattr and bpf_remove_dentry_xattr BPF kfuncs attempt to lock the inode of the supplied dentry without checking if it is NULL. If a negative dentry is passed (e.g. from security_inode_create), d_inode(dentry) returns NULL, and inode_lock(inode) will cause a NULL pointer dereference.
Trivially fix this by adding a NULL check for inode before attempting to lock it, returning -EINVAL if it is NULL.
Additionally, drop WARN_ON(!inode) in bpf_xattr_read_permission() and bpf_xattr_write_permission(). These warnings could be triggered by passing a negative dentry to bpf_get_dentry_xattr() or the _locked variants of the xattr kfuncs, potentially causing a Denial of Service on systems with panic_on_warn enabled. Instead, simply return -EINVAL.
Which versions are affected by CVE-2026-74400?
How do I fix CVE-2026-74400?
Apply the vendor's patch.
Is CVE-2026-74400 being exploited?
There is no known exploitation of CVE-2026-74400 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-74400, DEBIAN-CVE-2026-74400, GHSA-vrq8-fr7j-453w, UBUNTU-CVE-2026-74400.