{"id":"CVE-2026-74637","summary":"perf/core: Fix group leader use-after-free after sibling detach","details":"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-\u003esibling_list but leaving S-\u003egroup_leader == L.\n  - L is later closed and freed.\n  - A PERF_IOC_FLAG_GROUP ioctl on S follows S-\u003egroup_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.","modified":"2026-08-28T03:47:18.134413266Z","published":"2026-08-22T15:32:16.755Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74637.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/1e7abfeb23c12bf46f6457e4a3e1a1a300d50619"},{"type":"WEB","url":"https://git.kernel.org/stable/c/42c5ca1f0a288a52878bd72a5595b08261057438"},{"type":"WEB","url":"https://git.kernel.org/stable/c/80c6054a4c40a0ffad82acef9f9a0dee108d152a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8e92e03984364d93e0d5b0acd81c95eca773f034"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8f867c0e8da4c2303d91adf45acb6b1820966c27"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a979a642402d0b1f856c7a729b4cb2d92de4cf2f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b42948f9e0d1ea4dbd5742ce1dfc7688de5d4a35"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f8a07021679aadfb6d63b209207ccc41f26982d1"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74637.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74637"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"8a49542c0554af7d0073aac0ee73ee65b807ef34"},{"fixed":"8f867c0e8da4c2303d91adf45acb6b1820966c27"},{"fixed":"8e92e03984364d93e0d5b0acd81c95eca773f034"},{"fixed":"f8a07021679aadfb6d63b209207ccc41f26982d1"},{"fixed":"80c6054a4c40a0ffad82acef9f9a0dee108d152a"},{"fixed":"b42948f9e0d1ea4dbd5742ce1dfc7688de5d4a35"},{"fixed":"a979a642402d0b1f856c7a729b4cb2d92de4cf2f"},{"fixed":"1e7abfeb23c12bf46f6457e4a3e1a1a300d50619"},{"fixed":"42c5ca1f0a288a52878bd72a5595b08261057438"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"0"},{"last_affected":"e732ebc42aea321ee84514330eb3a675307fcc83"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"2.6.34.14"},{"fixed":"2.6.35"}]}],"versions":["v2.6.34.13","v2.6.34.12","v2.6.34.11","v2.6.34.10","v2.6.34.9","v2.6.34.8","v2.6.34.7","v2.6.34.6","v2.6.34.5","v2.6.34.4","v2.6.34.3","v2.6.34.2","v2.6.34.1","v2.6.34","v2.6.34-rc7","v2.6.34-rc6","v2.6.34-rc5","v2.6.34-rc4","v2.6.34-rc3","v2.6.34-rc2","v2.6.34-rc1","v2.6.33","v2.6.33-rc6","v2.6.33-rc8","v2.6.33-rc4","v2.6.33-rc5","v2.6.33-rc3","v2.6.33-rc7","v2.6.33-rc2","v2.6.32","v2.6.33-rc1","v2.6.32-rc8","v2.6.32-rc7","v2.6.32-rc6","v2.6.31","v2.6.32-rc5","v2.6.32-rc4","v2.6.32-rc2","v2.6.32-rc1","v2.6.32-rc3","v2.6.31-rc9","v2.6.31-rc1","v2.6.31-rc7","v2.6.31-rc8","v2.6.31-rc6","v2.6.30-rc6","v2.6.30","v2.6.31-rc4","v2.6.31-rc5","v2.6.31-rc3","v2.6.31-rc2","v2.6.30-rc7","v2.6.30-rc8","v2.6.30-rc5","v2.6.30-rc3","v2.6.30-rc4","v2.6.30-rc1","v2.6.30-rc2","v2.6.29","v2.6.29-rc8","v2.6.29-rc7","v2.6.29-rc5","v2.6.29-rc1","v2.6.29-rc6","v2.6.29-rc4","v2.6.29-rc3","v2.6.29-rc2","v2.6.28","v2.6.28-rc7","v2.6.28-rc9","v2.6.28-rc8","v2.6.28-rc6","v2.6.28-rc5","v2.6.28-rc4","v2.6.28-rc2","v2.6.28-rc3","v2.6.28-rc1","v2.6.27","v2.6.27-rc7","v2.6.27-rc9","v2.6.27-rc8","v2.6.27-rc5","v2.6.27-rc6","v2.6.27-rc4","v2.6.27-rc1","v2.6.27-rc3","v2.6.27-rc2","v2.6.26","v2.6.26-rc9","v2.6.26-rc8","v2.6.26-rc3","v2.6.26-rc7","v2.6.26-rc6","v2.6.26-rc5","v2.6.26-rc4","v2.6.26-rc2","v2.6.26-rc1","v2.6.25","v2.6.25-rc7","v2.6.25-rc9","v2.6.25-rc8","v2.6.25-rc6","v2.6.25-rc5","v2.6.25-rc3","v2.6.25-rc4","v2.6.24","v2.6.25-rc2","v2.6.25-rc1","v2.6.24-rc8","v2.6.24-rc7","v2.6.24-rc6","v2.6.24-rc5","v2.6.24-rc4","v2.6.24-rc3","v2.6.24-rc2","v2.6.24-rc1","v2.6.23","v2.6.23-rc9","v2.6.23-rc8","v2.6.23-rc5","v2.6.23-rc7","v2.6.23-rc6","v2.6.23-rc4","v2.6.23-rc3","v2.6.23-rc2","v2.6.23-rc1","v2.6.22","v2.6.22-rc7","v2.6.22-rc6","v2.6.22-rc5","v2.6.22-rc4","v2.6.22-rc3","v2.6.22-rc2","v2.6.22-rc1","v2.6.21","v2.6.21-rc7","v2.6.21-rc6","v2.6.21-rc5","v2.6.21-rc4","v2.6.21-rc3","v2.6.21-rc2","v2.6.21-rc1","v2.6.20-rc7","v2.6.20-rc6","v2.6.20-rc5","v2.6.20-rc4","v2.6.20-rc3","v2.6.20-rc1","v2.6.20-rc2","v2.6.19-rc2","v2.6.18","v2.6.19-rc1","v2.6.18-rc6","v2.6.18-rc5","v2.6.18-rc3","v2.6.18-rc2","v2.6.18-rc1","v2.6.17","v2.6.17-rc4","v2.6.17-rc6","v2.6.17-rc5","v2.6.17-rc3","v2.6.17-rc2","v2.6.17-rc1","v2.6.16","v2.6.16-rc6","v2.6.16-rc4","v2.6.16-rc5","v2.6.16-rc3","v2.6.16-rc2","v2.6.16-rc1","v2.6.15-rc7","v2.6.15-rc5","v2.6.15-rc4","v2.6.15-rc2","v2.6.15-rc1","v2.6.14-rc3","v2.6.14-rc2","v2.6.14-rc1","v2.6.13","v2.6.13-rc7","v2.6.13-rc6","v2.6.13-rc5","v2.6.13-rc3","v2.6.13-rc4","v2.6.13-rc2","v2.6.13-rc1","v2.6.12-rc4","v2.6.12-rc3","v2.6.12-rc2"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74637.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"ty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