CVE-2025-40109 crypto: rng - Ensure set_ent is always present
A missing function pointer in the Linux kernel crypto RNG can cause a null pointer dereference, leading to a system crash.
- 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-2025-40109?
CVE-2025-40109 is a vulnerability in Linux, published on 9 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:
crypto: rng - Ensure set_ent is always present
Ensure that set_ent is always set since only drbg provides it.
Which versions are affected by CVE-2025-40109?
How do I fix CVE-2025-40109?
Apply the vendor's patch.
Is CVE-2025-40109 being exploited?
There is no known exploitation of CVE-2025-40109 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2025-40109, DEBIAN-CVE-2025-40109, GHSA-r2qx-8vq2-jc32, ROOT-OS-DEBIAN-11-CVE-2025-40109, ROOT-OS-DEBIAN-13-CVE-2025-40109, ROOT-OS-UBUNTU-2204-CVE-2025-40109 and 2 more.