CVE-2026-90317 bpf: Invalidate RCU pointers after final spin unlock
A use-after-free in the Linux kernel BPF subsystem allows attackers to trigger memory corruption and potentially execute code or escalate privileges.
- 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-2026-90317?
CVE-2026-90317 is a high-severity use after free vulnerability in Linux, published on 17 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:
bpf: Invalidate RCU pointers after final spin unlock
In a sleepable BPF program, a spin lock can provide the only RCU protection for a kptr. The final bpf_spin_unlock() ends that protection, but the verifier leaves the pointer valid. Another CPU can then free the object before the pointer is used. A capability-limited runtime PoC triggered a task_struct use-after-free in __bpf_get_task_stack().
Record whether the program is in an RCU-protected context before releasing the lock. Invalidate RCU-protected pointers only when the unlock leaves the final such context. This preserves valid pointers in non-sleepable programs and inside an explicit RCU read-side section.
Which versions are affected by CVE-2026-90317?
How do I fix CVE-2026-90317?
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-2026-90317 being exploited?
There is no known exploitation of CVE-2026-90317 in the wild and no public exploit code.
Sources
Also known as AZL-102240, BELL-CVE-2026-90317, DEBIAN-CVE-2026-90317, GHSA-6jx2-qmxh-94v4, UBUNTU-CVE-2026-90317.