# CVE-2026-31528

> Vulnerability · severity: **HIGH** (CVSS 7.8).

## Description

In the Linux kernel, the following vulnerability has been resolved:

perf: Make sure to use pmu_ctx->pmu for groups

Oliver reported that x86_pmu_del() ended up doing an out-of-bound memory access
when group_sched_in() fails and needs to roll back.

This *should* be handled by the transaction callbacks, but he found that when
the group leader is a software event, the transaction handlers of the wrong PMU
are used. Despite the move_group case in perf_event_open() and group_sched_in()
using pmu_ctx->pmu.

Turns out, inherit uses event->pmu to clone the events, effectively undoing the
move_group case for all inherited contexts. Fix this by also making inherit use
pmu_ctx->pmu, ensuring all inherited counters end up in the same pmu context.

Similarly, __perf_event_read() should use equally use pmu_ctx->pmu for the
group case.

## Key facts

- **CVE ID:** CVE-2026-31528
- **Published:** 2026-04-22
- **CVSS severity:** HIGH
- **CVSS base score:** 7.8
- **CWE codes:** CWE-125

## Affected products

- `linux:linux_kernel`

## Primary sources

- NIST NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31528

## Citation

> AI Analytics. CVE-2026-31528. Retrieved 2026-07-31 from https://api.ai-analytics.org/cve/CVE-2026-31528. Derived from NIST NVD. Licensed CC0.

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