{"id":"DEBIAN-CVE-2026-74637","details":"In 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-\u003esibling_list but leaving S-\u003egroup_leader == L.   - L is later closed and freed.   - A PERF_IOC_FLAG_GROUP ioctl on S follows S-\u003egroup_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.","modified":"2026-09-19T22:01:35.628120622Z","published":"2026-08-22T16:16:36.890Z","upstream":["CVE-2026-74637"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-74637"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.187-1"}]}],"versions":["6.1.106-1","6.1.106-2","6.1.106-3","6.1.112-1","6.1.115-1","6.1.119-1","6.1.123-1","6.1.124-1","6.1.128-1","6.1.129-1","6.1.133-1","6.1.135-1","6.1.137-1","6.1.139-1","6.1.140-1","6.1.147-1","6.1.148-1","6.1.153-1","6.1.158-1","6.1.159-1","6.1.162-1","6.1.164-1","6.1.170-1","6.1.170-2","6.1.170-3","6.1.172-1","6.1.174-1","6.1.176-1","6.1.177-1","6.1.180-1","6.1.27-1","6.1.37-1","6.1.38-1","6.1.38-2","6.1.38-2~bpo11+1","6.1.38-3","6.1.38-4","6.1.38-4~bpo11+1","6.1.52-1","6.1.55-1","6.1.55-1~bpo11+1","6.1.64-1","6.1.66-1","6.1.67-1","6.1.69-1","6.1.69-1~bpo11+1","6.1.76-1","6.1.76-1~bpo11+1","6.1.82-1","6.1.85-1","6.1.90-1","6.1.90-1~bpo11+1","6.1.94-1","6.1.94-1~bpo11+1","6.1.98-1","6.1.99-1"],"ecosystem_specific":{"urgency":"not 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