CVE-2025-40101 btrfs: fix memory leaks when rejecting a non SINGLE data profile without an RST
A memory leak in the Linux kernel btrfs filesystem allows local attackers to cause denial of service by exhausting system memory.
- 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-2025-40101?
CVE-2025-40101 is a memory corruption vulnerability in Linux, published on 30 Oct 2025. 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 memory leaks when rejecting a non SINGLE data profile without an RST
At the end of btrfs_load_block_group_zone_info() the first thing we do is to ensure that if the mapping type is not a SINGLE one and there is no RAID stripe tree, then we return early with an error.
Doing that, though, prevents the code from running the last calls from this function which are about freeing memory allocated during its run. Hence, in this case, instead of returning early, we set the ret value and fall through the rest of the cleanup code.
Which versions are affected by CVE-2025-40101?
How do I fix CVE-2025-40101?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2025-40101 being exploited?
There is no known exploitation of CVE-2025-40101 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2025-40101, DEBIAN-CVE-2025-40101, GHSA-qqwh-7pmj-9xx8, ROOT-OS-DEBIAN-13-CVE-2025-40101, ROOT-OS-UBUNTU-2404-CVE-2025-40101, UBUNTU-CVE-2025-40101.