CVE-2025-40293 iommufd: Don't overflow during division for dirty tracking
A local attacker can trigger a divide-by-zero error in the Linux kernel's iommufd dirty tracking, causing a system crash.
- 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-2025-40293?
CVE-2025-40293 is a vulnerability in Linux, published on 8 Dec 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:
iommufd: Don't overflow during division for dirty tracking
If pgshift is 63 then BITS_PER_TYPE(*bitmap->bitmap) * pgsize will overflow to 0 and this triggers divide by 0.
In this case the index should just be 0, so reorganize things to divide by shift and avoid hitting any overflows.
Which versions are affected by CVE-2025-40293?
How do I fix CVE-2025-40293?
Apply the vendor's patch.
Is CVE-2025-40293 being exploited?
There is no known exploitation of CVE-2025-40293 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2025-40293, DEBIAN-CVE-2025-40293, GHSA-q92x-chq8-5c2g, ROOT-OS-DEBIAN-12-CVE-2025-40293, ROOT-OS-DEBIAN-13-CVE-2025-40293, ROOT-OS-UBUNTU-2404-CVE-2025-40293 and 1 more.