CVE-2026-90247 bpf: Fix mmap_lock leak in irq_work path
A race condition in the Linux kernel BPF subsystem can leak mmap locks, causing a denial of service by blocking memory management operations.
- 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-2026-90247?
CVE-2026-90247 is a denial of service 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: Fix mmap_lock leak in irq_work path
stack_map_get_build_id_offset() introduced a per-CPU irq_work to defer mmap_read_unlock() from NMI context, and bpf_find_vma() later reused the same mmap_unlock_work. Both callers only check whether the work is busy before taking mmap_lock, so a nested caller can reuse the slot before the first caller queues it. Two read locks may then be acquired while only one deferred unlock runs, leaking a read lock and blocking exit_mmap().
Reserve the per-CPU slot before mmap_read_trylock(). Use the same wrapper in stackmap and bpf_find_vma() so both callers release the reservation on trylock failure. Keep rejecting the slot while the irq_work remains busy. Release it after the irq_work callback unlocks the mm.
Which versions are affected by CVE-2026-90247?
How do I fix CVE-2026-90247?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-90247 being exploited?
There is no known exploitation of CVE-2026-90247 in the wild and no public exploit code.
Sources
Also known as AZL-102864, BELL-CVE-2026-90247, DEBIAN-CVE-2026-90247, GHSA-m447-wf7w-9qp4, UBUNTU-CVE-2026-90247.