CVE-2026-80626 powerpc/perf: fix preempt count underflow in fsl_emb_pmu_del
A local attacker can trigger a preempt count underflow in the PowerPC performance monitor driver, causing a kernel bug and 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-2026-80626?
CVE-2026-80626 is a vulnerability in Linux, published on 28 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:
powerpc/perf: fix preempt count underflow in fsl_emb_pmu_del
fsl_emb_pmu_del() unconditionally calls put_cpu_var(cpu_hw_events) at the 'out:' label, but only calls the matching get_cpu_var() after the 'i < 0' early-return check. When event->hw.idx is negative the function jumps to 'out:' without having taken get_cpu_var(), and the trailing put_cpu_var() then issues an unmatched preempt_enable(), underflowing preempt_count.
On a CONFIG_PREEMPT=y kernel preempt_count would underflow and eventually present as a 'scheduling while atomic' BUG.
Move put_cpu_var() to pair with get_cpu_var() so the percpu access is correctly bracketed and the 'out:' label only handles perf_pmu_enable.
Which versions are affected by CVE-2026-80626?
How do I fix CVE-2026-80626?
Apply the vendor's patch.
Is CVE-2026-80626 being exploited?
There is no known exploitation of CVE-2026-80626 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-80626, DEBIAN-CVE-2026-80626, GHSA-j46p-7hmv-qpv9, UBUNTU-CVE-2026-80626.