CVE-2026-74634 ring-buffer: Prevent subbuf order change when resizing is disabled
A use-after-free vulnerability in the Linux kernel ring buffer allows attackers to potentially execute code or escalate privileges when resizing is disabled.
- 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-2026-74634?
CVE-2026-74634 is a high-severity use after free vulnerability in Linux, published on 22 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:
ring-buffer: Prevent subbuf order change when resizing is disabled
Because ring_buffer_subbuf_order_set() frees buffer pages, we can't allow it when resizing is disabled. A non-consuming reader is at risk of use-after-free (rb_advance_iter()).
Return -EBUSY on resize_disabled, matching ring_buffer_resize() behaviour.
Which versions are affected by CVE-2026-74634?
How do I fix CVE-2026-74634?
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-2026-74634 being exploited?
There is no known exploitation of CVE-2026-74634 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-74634, DEBIAN-CVE-2026-74634, GHSA-cq5j-7xcv-jwf8, UBUNTU-CVE-2026-74634.