perf/core: Fix group leader use-after-free after sibling detach

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-74637
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-22 16:16:36 UTC
Updated2026-08-27 13:18:35 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: perf/core: Fix group leader use-after-free after sibling detach perf_group_detach() handles leader and sibling detach differently. When the group leader is detached, all siblings are promoted to singleton events and their group_leader pointer is reset to themselves. When a sibling is detached, it is removed from the leader's sibling_list, but its group_leader pointer is left pointing at the old leader. That is harmless when the sibling is being closed and freed immediately, as in the DETACH_DEAD path. It is not safe when the sibling is detached but kept alive, such as during CPU hotplug with DETACH_GROUP. In that case the sibling is removed from the context, while its file descriptor can still keep it alive. A typical failing sequence is: - A group contains leader L and sibling S. - CPU hot-unplug detaches S with DETACH_GROUP, removing it from L->sibling_list but leaving S->group_leader == L. - L is later closed and freed. - A PERF_IOC_FLAG_GROUP ioctl on S follows S->group_leader and dereferences the freed leader. This was reproduced by running the perf event fuzzer, CPU hotplug, and a stress workload concurrently: Unable to handle kernel paging request at virtual address 006b6b6b6b6b6cdb CPU: 2 PID: 12489 Comm: perf_fuzzer 6.18.7 PREEMPT pc : perf_ioctl+0x34c/0xc68 x20: ffffff89a3fa2c70 x8 : 6b6b6b6b6b6b6b6b Code: 943c4a0e 340047a0 f9404a94 f9411e88 (f940b908) Call trace: perf_ioctl+0x34c/0xc68 (P) __arm64_sys_ioctl+0xa0/0xf4 invoke_syscall+0x58/0xe4 el0_svc_common+0xa8/0xdc do_el0_svc+0x1c/0x28 el0_svc+0x40/0xc0 el0t_64_sync_handler+0x68/0xdc el0t_64_sync+0x1c4/0x1c8 The fault happened in perf_ioctl(), where perf_event_for_each() follows the stale group_leader pointer and perf_event_for_each_child() then dereferences the freed leader's context. Fix the use-after-free by promoting the detached sibling to a singleton. Also fix __event_disable() cgroup accounting and event state change.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.001250000 probability, percentile 0.024880000 (date 2026-08-27)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 8a49542c0554af7d0073aac0ee73ee65b807ef34 8f867c0e8da4c2303d91adf45acb6b1820966c27 git Not specified
CNA Linux Linux affected 8a49542c0554af7d0073aac0ee73ee65b807ef34 8e92e03984364d93e0d5b0acd81c95eca773f034 git Not specified
CNA Linux Linux affected 8a49542c0554af7d0073aac0ee73ee65b807ef34 f8a07021679aadfb6d63b209207ccc41f26982d1 git Not specified
CNA Linux Linux affected 8a49542c0554af7d0073aac0ee73ee65b807ef34 80c6054a4c40a0ffad82acef9f9a0dee108d152a git Not specified
CNA Linux Linux affected 8a49542c0554af7d0073aac0ee73ee65b807ef34 b42948f9e0d1ea4dbd5742ce1dfc7688de5d4a35 git Not specified
CNA Linux Linux affected 8a49542c0554af7d0073aac0ee73ee65b807ef34 a979a642402d0b1f856c7a729b4cb2d92de4cf2f git Not specified
CNA Linux Linux affected 8a49542c0554af7d0073aac0ee73ee65b807ef34 1e7abfeb23c12bf46f6457e4a3e1a1a300d50619 git Not specified
CNA Linux Linux affected 8a49542c0554af7d0073aac0ee73ee65b807ef34 42c5ca1f0a288a52878bd72a5595b08261057438 git Not specified
CNA Linux Linux affected e732ebc42aea321ee84514330eb3a675307fcc83 git Not specified
CNA Linux Linux affected 2.6.34.14 2.6.35 semver Not specified
CNA Linux Linux affected 2.6.35 Not specified
CNA Linux Linux unaffected 2.6.35 semver Not specified
CNA Linux Linux unaffected 5.10.267 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.218 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.185 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.154 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.105 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.45 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.9 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/a979a642402d0b1f856c7a729b4cb2d92de4cf2f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/8e92e03984364d93e0d5b0acd81c95eca773f034 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/42c5ca1f0a288a52878bd72a5595b08261057438 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/1e7abfeb23c12bf46f6457e4a3e1a1a300d50619 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/80c6054a4c40a0ffad82acef9f9a0dee108d152a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b42948f9e0d1ea4dbd5742ce1dfc7688de5d4a35 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/f8a07021679aadfb6d63b209207ccc41f26982d1 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/8f867c0e8da4c2303d91adf45acb6b1820966c27 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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