CVE-2026-98015 net/mlx5: E-Switch: fix use-after-free in mlx5_eswitch_termtbl_put
A use-after-free in the Linux kernel mlx5 E-Switch driver allows local attackers to execute arbitrary code or escalate privileges via race conditions.
- 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-2026-98015?
CVE-2026-98015 is an use after free vulnerability in Linux, published on 25 Sep 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:
net/mlx5: E-Switch: fix use-after-free in mlx5_eswitch_termtbl_put
In mlx5_eswitch_termtbl_put(), the zero-ref cleanup check reads tt->ref_count after termtbl_mutex has been released. Two concurrent callers on the same mlx5_termtbl_handle race: one decrements ref_count to zero, removes the hash entry, and calls kfree(tt) while the other has already dropped the mutex and is about to evaluate if (!tt->ref_count), producing a use-after-free.
Fix this by capturing the result of the decrement into a stack-local last variable before dropping the mutex. The cleanup decision is now made entirely under termtbl_mutex, and tt is not touched after kfree.
Which versions are affected by CVE-2026-98015?
How do I fix CVE-2026-98015?
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-2026-98015 being exploited?
There is no known exploitation of CVE-2026-98015 in the wild and no public exploit code.
Sources
Also known as AZL-104298, BELL-CVE-2026-98015, DEBIAN-CVE-2026-98015, GHSA-wg7p-rcj6-hf3p, UBUNTU-CVE-2026-98015.