CVE-2026-43115 srcu: Use irq_work to start GP in tiny SRCU
A use-after-free vulnerability in the Linux kernel's tiny SRCU implementation allows attackers to potentially execute code or cause a denial of service.
- 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-2026-43115?
CVE-2026-43115 is a medium-severity use after free vulnerability in Linux kernel, published on 6 May 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:
srcu: Use irq_work to start GP in tiny SRCU
Tiny SRCU's srcu_gp_start_if_needed() directly calls schedule_work(), which acquires the workqueue pool->lock.
This causes a lockdep splat when call_srcu() is called with a scheduler lock held, due to:
call_srcu() [holding pi_lock] srcu_gp_start_if_needed() schedule_work() -> pool->lock
workqueue_init() / create_worker() [holding pool->lock] wake_up_process() -> try_to_wake_up() -> pi_lock
Also add irq_work_sync() to cleanup_srcu_struct() to prevent a use-after-free if a queued irq_work fires after cleanup begins.
Tested with rcutorture SRCU-T and no lockdep warnings.
[ Thanks to Boqun for similar fix in patch "rcu: Use an intermediate irq_work to start process_srcu()" ]
Which versions are affected by CVE-2026-43115?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-43115?
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-2026-43115 being exploited?
There is no known exploitation of CVE-2026-43115 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-43115, DEBIAN-CVE-2026-43115, GHSA-vj6f-v49f-r83x, ROOT-OS-DEBIAN-11-CVE-2026-43115, ROOT-OS-DEBIAN-12-CVE-2026-43115, ROOT-OS-DEBIAN-13-CVE-2026-43115 and 3 more.