# CVE-2026-99187: perf: Fix perf_pmu_migrate_context() leaving events behind

CVE-2026-99187 is fixed in linux on 1 platform, first by DEBIAN-CVE-2026-99187, released November 3, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-99187
- Priority: Routine
- CVSS: 5.5 (Moderate)
- EPSS: 0.0017
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Oct 28, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-99187

## Description

In the Linux kernel, the following vulnerability has been resolved:  perf: Fix perf_pmu_migrate_context() leaving events behind  __perf_pmu_remove() walks the group leaders of a CPU and PMU with perf_event_groups_for_cpu_pmu(), removing each one as it goes. perf_remove_from_context() takes the leader out of the groups rbtree, after which rb_next() on that node returns NULL, prematurely ending the walk. Other groups stay behind in the source context.  On CPU hotplug, they are then torn down with the dying CPU. They keep running until teardown, while the PMU's interrupt and migrated events are on a new CPU, which drivers rely on never happening.  Walk ctx->event_list instead and pick out the PMU's events by their pmu_ctx.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 13.5 (trixie) | 6.12.115-2 | [DEBIAN-CVE-2026-99187](https://patchblox.com/security/data/fix/linux/debian-cve-2026-99187.md) | Nov 3, 2026 |
| Linux | linux Debian 14 | 7.2.13-1 | [DEBIAN-CVE-2026-99187](https://patchblox.com/security/data/fix/linux/debian-cve-2026-99187.md) | Nov 3, 2026 |

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Data as of 2026-11-08T19:12:23Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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