CVE-2026-74314 bpf: Cancel special fields on map value recycle
A race condition in Linux kernel BPF map recycling causes unsafe destructor calls in NMI contexts, potentially leading to system crashes.
- 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-2026-74314?
CVE-2026-74314 is a high-severity vulnerability in Linux, published on 15 Aug 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: Cancel special fields on map value recycle
Map update and delete paths currently call bpf_obj_free_fields() when a value is being replaced or recycled. That makes field destruction depend on the context of the update/delete operation. For tracing programs this can include NMI context, where referenced kptr destructors, uptr unpinning, and graph root destruction are not generally safe.
Introduce bpf_obj_cancel_fields() for the reusable-value path. It only performs NMI-safe cleanup for timer, workqueue, and task_work fields. Fields that need full destruction are left attached to the recycled value and are destroyed by the final cleanup path instead.
Switch array and hashtab update/delete/recycle paths to this cancel helper. Keep bpf_obj_free_fields() for final map destruction and for bpf_mem_alloc destructors. Preallocated hashtabs do not have allocator destructors, so teardown continues to walk the normal and extra elements and fully destroy their fields.
This deliberately relaxes the eager-free semantics of map update/delete for special fields. Programs that relied on a recycled map slot becoming empty immediately after update/delete were relying on behavior that cannot be implemented safely from every BPF execution context without offloading arbitrary destructors.
There is a chance this change breaks programs making assumptions regarding the eager freeing of fields. If so, we can relax semantics to cancellation only when irqs_disabled() is true in the future. However, theoretically, map values that get reused eagerly already have weaker guarantees as parallel users can recreate freed fields before the new element becomes visible again.
Which versions are affected by CVE-2026-74314?
How do I fix CVE-2026-74314?
Apply the vendor's patch.
Is CVE-2026-74314 being exploited?
There is no known exploitation of CVE-2026-74314 in the wild and no public exploit code.
Sources
Also known as AZL-96441, BELL-CVE-2026-74314, DEBIAN-CVE-2026-74314, GHSA-84mh-pvr2-7x86, UBUNTU-CVE-2026-74314.