{"api_version":"1","generated_at":"2026-08-22T17:47:27+00:00","cve":"CVE-2026-74637","urls":{"html":"https://cve.report/CVE-2026-74637","api":"https://cve.report/api/cve/CVE-2026-74637.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-74637","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-74637"},"summary":{"title":"perf/core: Fix group leader use-after-free after sibling detach","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nperf/core: Fix group leader use-after-free after sibling detach\n\nperf_group_detach() handles leader and sibling detach differently. When the\ngroup leader is detached, all siblings are promoted to singleton events and\ntheir group_leader pointer is reset to themselves. When a sibling is\ndetached, it is removed from the leader's sibling_list, but its\ngroup_leader pointer is left pointing at the old leader.\n\nThat is harmless when the sibling is being closed and freed immediately, as\nin the DETACH_DEAD path. It is not safe when the sibling is detached but\nkept alive, such as during CPU hotplug with DETACH_GROUP. In that case the\nsibling is removed from the context, while its file descriptor can still\nkeep it alive.\n\nA typical failing sequence is:\n\n  - A group contains leader L and sibling S.\n  - CPU hot-unplug detaches S with DETACH_GROUP, removing it from\n    L->sibling_list but leaving S->group_leader == L.\n  - L is later closed and freed.\n  - A PERF_IOC_FLAG_GROUP ioctl on S follows S->group_leader and\n    dereferences the freed leader.\n\nThis was reproduced by running the perf event fuzzer, CPU hotplug, and a\nstress workload concurrently:\n\n  Unable to handle kernel paging request at virtual address 006b6b6b6b6b6cdb\n  CPU: 2 PID: 12489 Comm: perf_fuzzer 6.18.7 PREEMPT\n  pc : perf_ioctl+0x34c/0xc68\n  x20: ffffff89a3fa2c70 x8 : 6b6b6b6b6b6b6b6b\n  Code: 943c4a0e 340047a0 f9404a94 f9411e88 (f940b908)\n  Call trace:\n  perf_ioctl+0x34c/0xc68 (P)\n  __arm64_sys_ioctl+0xa0/0xf4\n  invoke_syscall+0x58/0xe4\n  el0_svc_common+0xa8/0xdc\n  do_el0_svc+0x1c/0x28\n  el0_svc+0x40/0xc0\n  el0t_64_sync_handler+0x68/0xdc\n  el0t_64_sync+0x1c4/0x1c8\n\nThe fault happened in perf_ioctl(), where perf_event_for_each() follows\nthe stale group_leader pointer and perf_event_for_each_child() then\ndereferences the freed leader's context.\n\nFix the use-after-free by promoting the detached sibling to a singleton.\nAlso fix __event_disable() cgroup accounting and event state change.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-08-22 16:16:36","updated_at":"2026-08-22 16:16:36"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/a979a642402d0b1f856c7a729b4cb2d92de4cf2f","name":"https://git.kernel.org/stable/c/a979a642402d0b1f856c7a729b4cb2d92de4cf2f","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/42c5ca1f0a288a52878bd72a5595b08261057438","name":"https://git.kernel.org/stable/c/42c5ca1f0a288a52878bd72a5595b08261057438","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/1e7abfeb23c12bf46f6457e4a3e1a1a300d50619","name":"https://git.kernel.org/stable/c/1e7abfeb23c12bf46f6457e4a3e1a1a300d50619","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-74637","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74637","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 8a49542c0554af7d0073aac0ee73ee65b807ef34 a979a642402d0b1f856c7a729b4cb2d92de4cf2f git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 8a49542c0554af7d0073aac0ee73ee65b807ef34 1e7abfeb23c12bf46f6457e4a3e1a1a300d50619 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 8a49542c0554af7d0073aac0ee73ee65b807ef34 42c5ca1f0a288a52878bd72a5595b08261057438 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e732ebc42aea321ee84514330eb3a675307fcc83 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2.6.34.14 2.6.35 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2.6.35","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 2.6.35 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.45 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1.9 7.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["kernel/events/core.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"a979a642402d0b1f856c7a729b4cb2d92de4cf2f","status":"affected","version":"8a49542c0554af7d0073aac0ee73ee65b807ef34","versionType":"git"},{"lessThan":"1e7abfeb23c12bf46f6457e4a3e1a1a300d50619","status":"affected","version":"8a49542c0554af7d0073aac0ee73ee65b807ef34","versionType":"git"},{"lessThan":"42c5ca1f0a288a52878bd72a5595b08261057438","status":"affected","version":"8a49542c0554af7d0073aac0ee73ee65b807ef34","versionType":"git"},{"status":"affected","version":"e732ebc42aea321ee84514330eb3a675307fcc83","versionType":"git"},{"lessThan":"2.6.35","status":"affected","version":"2.6.34.14","versionType":"semver"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["kernel/events/core.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"2.6.35"},{"lessThan":"2.6.35","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.45","versionType":"semver"},{"lessThanOrEqual":"7.1.*","status":"unaffected","version":"7.1.9","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.2","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.45","versionStartIncluding":"2.6.35","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1.9","versionStartIncluding":"2.6.35","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2","versionStartIncluding":"2.6.35","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.34.14","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nperf/core: Fix group leader use-after-free after sibling detach\n\nperf_group_detach() handles leader and sibling detach differently. When the\ngroup leader is detached, all siblings are promoted to singleton events and\ntheir group_leader pointer is reset to themselves. When a sibling is\ndetached, it is removed from the leader's sibling_list, but its\ngroup_leader pointer is left pointing at the old leader.\n\nThat is harmless when the sibling is being closed and freed immediately, as\nin the DETACH_DEAD path. It is not safe when the sibling is detached but\nkept alive, such as during CPU hotplug with DETACH_GROUP. In that case the\nsibling is removed from the context, while its file descriptor can still\nkeep it alive.\n\nA typical failing sequence is:\n\n  - A group contains leader L and sibling S.\n  - CPU hot-unplug detaches S with DETACH_GROUP, removing it from\n    L->sibling_list but leaving S->group_leader == L.\n  - L is later closed and freed.\n  - A PERF_IOC_FLAG_GROUP ioctl on S follows S->group_leader and\n    dereferences the freed leader.\n\nThis was reproduced by running the perf event fuzzer, CPU hotplug, and a\nstress workload concurrently:\n\n  Unable to handle kernel paging request at virtual address 006b6b6b6b6b6cdb\n  CPU: 2 PID: 12489 Comm: perf_fuzzer 6.18.7 PREEMPT\n  pc : perf_ioctl+0x34c/0xc68\n  x20: ffffff89a3fa2c70 x8 : 6b6b6b6b6b6b6b6b\n  Code: 943c4a0e 340047a0 f9404a94 f9411e88 (f940b908)\n  Call trace:\n  perf_ioctl+0x34c/0xc68 (P)\n  __arm64_sys_ioctl+0xa0/0xf4\n  invoke_syscall+0x58/0xe4\n  el0_svc_common+0xa8/0xdc\n  do_el0_svc+0x1c/0x28\n  el0_svc+0x40/0xc0\n  el0t_64_sync_handler+0x68/0xdc\n  el0t_64_sync+0x1c4/0x1c8\n\nThe fault happened in perf_ioctl(), where perf_event_for_each() follows\nthe stale group_leader pointer and perf_event_for_each_child() then\ndereferences the freed leader's context.\n\nFix the use-after-free by promoting the detached sibling to a singleton.\nAlso fix __event_disable() cgroup accounting and event state change."}],"providerMetadata":{"dateUpdated":"2026-08-22T15:32:16.755Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/a979a642402d0b1f856c7a729b4cb2d92de4cf2f"},{"url":"https://git.kernel.org/stable/c/1e7abfeb23c12bf46f6457e4a3e1a1a300d50619"},{"url":"https://git.kernel.org/stable/c/42c5ca1f0a288a52878bd72a5595b08261057438"}],"title":"perf/core: Fix group leader use-after-free after sibling detach","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-74637","datePublished":"2026-08-22T15:32:16.755Z","dateReserved":"2026-08-15T05:44:03.922Z","dateUpdated":"2026-08-22T15:32:16.755Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-22 16:16:36","lastModifiedDate":"2026-08-22 16:16:36","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"74637","Ordinal":"1","Title":"perf/core: Fix group leader use-after-free after sibling detach","CVE":"CVE-2026-74637","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"74637","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nperf/core: Fix group leader use-after-free after sibling detach\n\nperf_group_detach() handles leader and sibling detach differently. When the\ngroup leader is detached, all siblings are promoted to singleton events and\ntheir group_leader pointer is reset to themselves. When a sibling is\ndetached, it is removed from the leader's sibling_list, but its\ngroup_leader pointer is left pointing at the old leader.\n\nThat is harmless when the sibling is being closed and freed immediately, as\nin the DETACH_DEAD path. It is not safe when the sibling is detached but\nkept alive, such as during CPU hotplug with DETACH_GROUP. In that case the\nsibling is removed from the context, while its file descriptor can still\nkeep it alive.\n\nA typical failing sequence is:\n\n  - A group contains leader L and sibling S.\n  - CPU hot-unplug detaches S with DETACH_GROUP, removing it from\n    L->sibling_list but leaving S->group_leader == L.\n  - L is later closed and freed.\n  - A PERF_IOC_FLAG_GROUP ioctl on S follows S->group_leader and\n    dereferences the freed leader.\n\nThis was reproduced by running the perf event fuzzer, CPU hotplug, and a\nstress workload concurrently:\n\n  Unable to handle kernel paging request at virtual address 006b6b6b6b6b6cdb\n  CPU: 2 PID: 12489 Comm: perf_fuzzer 6.18.7 PREEMPT\n  pc : perf_ioctl+0x34c/0xc68\n  x20: ffffff89a3fa2c70 x8 : 6b6b6b6b6b6b6b6b\n  Code: 943c4a0e 340047a0 f9404a94 f9411e88 (f940b908)\n  Call trace:\n  perf_ioctl+0x34c/0xc68 (P)\n  __arm64_sys_ioctl+0xa0/0xf4\n  invoke_syscall+0x58/0xe4\n  el0_svc_common+0xa8/0xdc\n  do_el0_svc+0x1c/0x28\n  el0_svc+0x40/0xc0\n  el0t_64_sync_handler+0x68/0xdc\n  el0t_64_sync+0x1c4/0x1c8\n\nThe fault happened in perf_ioctl(), where perf_event_for_each() follows\nthe stale group_leader pointer and perf_event_for_each_child() then\ndereferences the freed leader's context.\n\nFix the use-after-free by promoting the detached sibling to a singleton.\nAlso fix __event_disable() cgroup accounting and event state change.","Type":"Description","Title":"perf/core: Fix group leader use-after-free after sibling detach"}]}}}