CVE-2026-99144 sched_ext: Fix use-after-free of a destroyed user DSQ by a deferred reenqueue
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-99144?
CVE-2026-99144 is a vulnerability in Linux, published on 28 Oct 2026.
Official description
In the Linux kernel, the following vulnerability has been resolved:
sched_ext: Fix use-after-free of a destroyed user DSQ by a deferred reenqueue
A deferred reenqueue can read a freed user DSQ. The request stays on its CPU's deferred list until run_deferred() takes it, and the RCU callback that frees the DSQ assumes that the grace period has flushed it, so exit_dsq() checks the per-CPU node without the deferred list lock. A grace period waits for readers in flight, not for a pending run_deferred(). A run_deferred() which starts after the grace period began can detach the request right before the callback looks and then read the freed DSQ's id.
Cancel the pending requests before the grace period instead. The irq work that frees the DSQ unlinks every CPU's request under the per-CPU deferred list lock, and schedule_dsq_reenq() ignores a new request under the same lock once the id is invalid. Only a run_deferred() that started before the grace period can hold a request, and it runs with IRQs disabled, so the grace period waits for it and nothing touches the DSQ after the callback.
Which versions are affected by CVE-2026-99144?
How do I fix CVE-2026-99144?
Upgrade to a fixed version.
Is CVE-2026-99144 being exploited?
There is no known exploitation of CVE-2026-99144 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-99144, GHSA-mqg8-58gq-6w7m, UBUNTU-CVE-2026-99144.