CVE-2026-97949 configfs: unhash the dentry before dropping the item in rmdir
A use-after-free in the Linux kernel configfs subsystem allows local attackers to execute arbitrary code or escalate privileges via a race condition during directory removal.
- 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-2026-97949?
CVE-2026-97949 is an use after free vulnerability in Linux, published on 25 Sep 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:
configfs: unhash the dentry before dropping the item in rmdir
configfs_get_config_item() treats a hashed dentry as proof that sd->s_element is a live config_item. configfs_rmdir() breaks that: simple_rmdir() leaves the dentry hashed, the last reference to the item is dropped right after, and the dentry is only unhashed by d_delete() once ->rmdir() has returned. configfs_symlink() resolves its target holding no lock on it, so get_target() can land in that window:
BUG: KASAN: slab-use-after-free in config_item_get+0x26/0x90 get_target fs/configfs/symlink.c:128 [inline] configfs_symlink+0x4ab/0x1030 fs/configfs/symlink.c:185
Unhash in configfs_remove_dir(), while the item is still guaranteed to be there. A reference obtained just before that stays harmless, as create_link() rechecks CONFIGFS_USET_DROPPING, already set by configfs_detach_prep(). Both configfs_unregister_subsystem() paths d_drop() after detaching, so this only makes rmdir match them.
Which versions are affected by CVE-2026-97949?
How do I fix CVE-2026-97949?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-97949 being exploited?
There is no known exploitation of CVE-2026-97949 in the wild and no public exploit code.
Sources
Also known as AZL-104555, BELL-CVE-2026-97949, DEBIAN-CVE-2026-97949, GHSA-gmrw-x43x-r9qf, UBUNTU-CVE-2026-97949.