CVE-2025-39902 mm/slub: avoid accessing metadata when pointer is invalid in object_err()
A null pointer dereference in the Linux kernel's SLUB allocator debug code can cause a system crash when handling invalid pointers.
- 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-2025-39902?
CVE-2025-39902 is a high-severity vulnerability in Debian Debian Linux, published on 1 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:
mm/slub: avoid accessing metadata when pointer is invalid in object_err()
object_err() reports details of an object for further debugging, such as the freelist pointer, redzone, etc. However, if the pointer is invalid, attempting to access object metadata can lead to a crash since it does not point to a valid object.
One known path to the crash is when alloc_consistency_checks() determines the pointer to the allocated object is invalid because of a freelist corruption, and calls object_err() to report it. The debug code should report and handle the corruption gracefully and not crash in the process.
In case the pointer is NULL or check_valid_pointer() returns false for the pointer, only print the pointer value and skip accessing metadata.
Weakness: CWE-476
Which versions are affected by CVE-2025-39902?
It affects 2 products.
Products include Debian Debian Linux, Linux kernel.
How do I fix CVE-2025-39902?
Apply the vendor's patch.
Is CVE-2025-39902 being exploited?
There is no known exploitation of CVE-2025-39902 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as AZL-68019, BELL-CVE-2025-39902, DEBIAN-CVE-2025-39902, GHSA-27rc-rcpv-8mr7, ROOT-OS-DEBIAN-11-CVE-2025-39902, ROOT-OS-UBUNTU-2204-CVE-2025-39902 and 2 more.