CVE-2026-98244 btrfs: clear free space tree creation state on rebuild failure
A flaw in the Linux kernel's btrfs filesystem can cause denial of service by skipping delayed reference processing after a failed free space tree rebuild.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-98244?
CVE-2026-98244 is a denial of service vulnerability in Linux, published on 6 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:
btrfs: clear free space tree creation state on rebuild failure
btrfs_rebuild_free_space_tree() sets BTRFS_FS_CREATING_FREE_SPACE_TREE before rebuilding the free space tree. Several error paths return without clearing this flag.
The transaction restart failure path can leave the flag set on a live filesystem, causing delayed reference processing to be skipped. Clear it on all free space tree rebuild failure paths. Keep BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED set, since a failed rebuild leaves the free space tree untrusted. Callers must fall back to extent-tree caching.
Which versions are affected by CVE-2026-98244?
How do I fix CVE-2026-98244?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-98244 being exploited?
There is no known exploitation of CVE-2026-98244 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-98244, DEBIAN-CVE-2026-98244, GHSA-mg7q-63qp-3hvm, UBUNTU-CVE-2026-98244.