CVE-2025-40179 ext4: verify orphan file size is not too big
An attacker can cause excessive memory consumption and denial of service by mounting a filesystem with an absurdly large orphan file.
- 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-2025-40179?
CVE-2025-40179 is a denial of service vulnerability in Linux, published on 12 Nov 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:
ext4: verify orphan file size is not too big
In principle orphan file can be arbitrarily large. However orphan replay needs to traverse it all and we also pin all its buffers in memory. Thus filesystems with absurdly large orphan files can lead to big amounts of memory consumed. Limit orphan file size to a sane value and also use kvmalloc() for allocating array of block descriptor structures to avoid large order allocations for sane but large orphan files.
Which versions are affected by CVE-2025-40179?
How do I fix CVE-2025-40179?
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-2025-40179 being exploited?
There is no known exploitation of CVE-2025-40179 in the wild and no public exploit code.
Sources
Also known as AZL-70061, BELL-CVE-2025-40179, DEBIAN-CVE-2025-40179, GHSA-pf5x-wpf2-8vp9, ROOT-OS-DEBIAN-13-CVE-2025-40179, ROOT-OS-UBUNTU-2404-CVE-2025-40179 and 1 more.