CVE-2026-43359 btrfs: fix transaction abort on set received ioctl due to item overflow
A local user can trigger a filesystem read-only state by exploiting an item overflow in the btrfs set received ioctl, causing 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-2026-43359?
CVE-2026-43359 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: fix transaction abort on set received ioctl due to item overflow
If the set received ioctl fails due to an item overflow when attempting to add the BTRFS_UUID_KEY_RECEIVED_SUBVOL we have to abort the transaction since we did some metadata updates before.
This means that if a user calls this ioctl with the same received UUID field for a lot of subvolumes, we will hit the overflow, trigger the transaction abort and turn the filesystem into RO mode. A malicious user could exploit this, and this ioctl does not even requires that a user has admin privileges (CAP_SYS_ADMIN), only that he/she owns the subvolume.
Fix this by doing an early check for item overflow before starting a transaction. This is also race safe because we are holding the subvol_sem semaphore in exclusive (write) mode.
A test case for fstests will follow soon.
Weakness: CWE-191
Which versions are affected by CVE-2026-43359?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-43359?
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-2026-43359 being exploited?
There is no known exploitation of CVE-2026-43359 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-43359, DEBIAN-CVE-2026-43359, GHSA-63hq-hrgx-pfwm, ROOT-OS-DEBIAN-11-CVE-2026-43359, ROOT-OS-UBUNTU-2204-CVE-2026-43359, ROOT-OS-UBUNTU-2404-CVE-2026-43359 and 1 more.