CVE-2026-74637

Estado: RecibidaAlta (7.8)—

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.

Leer descripción completaMostrar menos

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:

This was reproduced by running the perf event fuzzer, CPU hotplug, and a stress workload concurrently:

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.

Detalles técnicos trazas, registros y código del informe original

  - 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.

  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

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Puntuación base: 7.8

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.13%
Percentil entre todas las CVEs puntuadas: 2
Fecha de la puntuación: 6/10/2026

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

ExplotaciónT1068 Exploitation for Privilege Escalationprivilege escalation85 %
Impacto principalT1499.004 Application or System Exploitationimpact75 %
Impacto secundarioT1561 Disk Wipeimpact60 %

Vulnerabilidad local (AV:L, PR:L) en kernel Linux que permite crash por use-after-free tras detach de sibling en perf events. Causa DoS y corrupción de memoria con impacto en disponibilidad e integridad del sistema.

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Threat Intelligence Program Filter Network Traffic Execution Prevention Application Isolation and Sandboxing Exploit Protection Update Software

Tecnologías afectadas (1)

⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.

Linux — Linux Kernel^AI

Referencias

JSON original (NVD)

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  "id": "CVE-2026-74637",
  "cveTags": [],
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        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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          "version": "3.1",
          "baseScore": 7.8,
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  "published": "2026-08-22T16:16:36.890",
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    }
  ],
  "vulnStatus": "Received",
  "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."
    }
  ],
  "lastModified": "2026-08-27T13:18:35.347",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}