CVE-2026-43308 btrfs: don't BUG() on unexpected delayed ref type in run_one_delayed_ref()
A local attacker can trigger a kernel crash by causing an unexpected delayed reference type in the Btrfs filesystem.
- 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-2026-43308?
CVE-2026-43308 is a medium-severity denial of service vulnerability in Linux kernel, published on 8 May 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: don't BUG() on unexpected delayed ref type in run_one_delayed_ref()
There is no need to BUG(), we can just return an error and log an error message.
Which versions are affected by CVE-2026-43308?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-43308?
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-2026-43308 being exploited?
There is no known exploitation of CVE-2026-43308 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-86205, BELL-CVE-2026-43308, DEBIAN-CVE-2026-43308, GHSA-mjx9-cr34-jhff, ROOT-OS-DEBIAN-11-CVE-2026-43308, ROOT-OS-DEBIAN-12-CVE-2026-43308 and 4 more.