Deadlock in Linux kernel - CVE-2026-98530

Vulnerability details

The vulnerability allows a local privileged user to cause a denial of service by permanently blocking kprobe optimizer flush operations and subsequent access to the kprobes optimization sysctl.

The vulnerability exists due to improper synchronization in the Linux kernel kprobe optimizer when flushing optimization work. A local privileged user can write 0 to /proc/sys/debug/kprobes-optimization while a kprobe is jump-optimized to leave the writer waiting indefinitely while holding kprobe_sysctl_mutex, blocking subsequent reads and writes to that sysctl. The optimizer incorrectly signals completion only when the completion is already done, and concurrent flushers can also reinitialize the shared completion and remove an existing waiter from its wait queue.

Affected software

How to mitigate CVE-2026-98530

External References

• https://git.kernel.org/stable/c/5bfa9f1a9dcb6ecb607adbc1c0226605c972935b
• https://git.kernel.org/stable/c/f05a01fc7d4f731b4c100d2aef1e85ad77728862

Related Security Bulletins

• Deadlock in Linux kernel kernel/kprobes.c: wait_for_kprobe_optimizer_locked() and kprobe_optimizer()
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux, linux-aws, linux-gcp and more