CVE-2026-45915 fat: avoid parent link count underflow in rmdir
A corrupted FAT image can cause an integer underflow in the Linux kernel's rmdir operation, leading to a system crash or 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-2026-45915?
CVE-2026-45915 is a medium-severity vulnerability in Linux kernel, published on 27 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:
fat: avoid parent link count underflow in rmdir
Corrupted FAT images can leave a directory inode with an incorrect i_nlink (e.g. 2 even though subdirectories exist). rmdir then unconditionally calls drop_nlink(dir) and can drive i_nlink to 0, triggering the WARN_ON in drop_nlink().
Add a sanity check in vfat_rmdir() and msdos_rmdir(): only drop the parent link count when it is at least 3, otherwise report a filesystem error.
Which versions are affected by CVE-2026-45915?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-45915?
Apply the vendor's patch.
Is CVE-2026-45915 being exploited?
There is no known exploitation of CVE-2026-45915 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-45915, DEBIAN-CVE-2026-45915, GHSA-2qhg-8p2v-wf99, ROOT-OS-UBUNTU-2204-CVE-2026-45915, ROOT-OS-UBUNTU-2404-CVE-2026-45915, UBUNTU-CVE-2026-45915.