CVE-2025-39826 net: rose: convert 'use' field to refcount_t
A race condition in the Linux kernel's ROSE network protocol allows use-after-free, potentially enabling code execution or privilege escalation.
- 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-2025-39826?
CVE-2025-39826 is a high-severity use after free vulnerability in Debian Debian Linux, published on 16 Sep 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:
net: rose: convert 'use' field to refcount_t
The 'use' field in struct rose_neigh is used as a reference counter but lacks atomicity. This can lead to race conditions where a rose_neigh structure is freed while still being referenced by other code paths.
For example, when rose_neigh->use becomes zero during an ioctl operation via rose_rt_ioctl(), the structure may be removed while its timer is still active, potentially causing use-after-free issues.
This patch changes the type of 'use' from unsigned short to refcount_t and updates all code paths to use rose_neigh_hold() and rose_neigh_put() which operate reference counts atomically.
Weakness: CWE-416
Which versions are affected by CVE-2025-39826?
It affects 2 products.
Products include Debian Debian Linux, Linux kernel.
How do I fix CVE-2025-39826?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2025-39826 being exploited?
There is no known exploitation of CVE-2025-39826 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as AZL-67434, BELL-CVE-2025-39826, DEBIAN-CVE-2025-39826, GHSA-xrj4-4g3m-87pf, ROOT-OS-DEBIAN-11-CVE-2025-39826, ROOT-OS-DEBIAN-12-CVE-2025-39826 and 4 more.