CVE-2026-74319 btrfs: zoned: fix deadlock waiting for ticket during data relocation
A deadlock in the Linux kernel's Btrfs zoned filesystem code allows local attackers to cause a denial of service during data relocation.
- 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-2026-74319?
CVE-2026-74319 is a denial of service 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:
btrfs: zoned: fix deadlock waiting for ticket during data relocation
When performing data relocation on a zoned filesystem, BTRFS can deadlock in handle_reserve_tickets(). The relocation process is waiting on a space reservation ticket that can never be fulfilled, because the relocation itself is the operation responsible for freeing up that space.
Fix this by introducing a new flush state, BTRFS_RESERVE_FLUSH_ZONED_RELOCATION, specifically for data chunk allocation during zoned relocation. Like BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE, this state uses priority_reclaim_data_space() instead of the normal flushing path, which avoids re-entering the relocation code and breaking the deadlock cycle.
In btrfs_alloc_data_chunk_ondemand(), select this new flush state when the inode belongs to a data relocation root on a zoned filesystem.
Which versions are affected by CVE-2026-74319?
How do I fix CVE-2026-74319?
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-2026-74319 being exploited?
There is no known exploitation of CVE-2026-74319 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-74319, GHSA-w48h-wv4w-hrq6, UBUNTU-CVE-2026-74319.