CVE-2026-23393
Estado: AnalizadaAlta (7.8)—
In the Linux kernel, the following vulnerability has been resolved:
bridge: cfm: Fix race condition in peer_mep deletion
When a peer MEP is being deleted, cancel_delayed_work_sync() is called on ccm_rx_dwork before freeing. However, br_cfm_frame_rx() runs in softirq context under rcu_read_lock (without RTNL) and can re-schedule ccm_rx_dwork via ccm_rx_timer_start() between cancel_delayed_work_sync() returning and kfree_rcu() being called.
The following is a simple race scenario:
To prevent this, cancel_delayed_work_sync() is replaced with disable_delayed_work_sync() in both peer MEP deletion paths, so that subsequent queue_delayed_work() calls from br_cfm_frame_rx() are silently rejected.
Leer descripción completaMostrar menos
The cc_peer_disable() helper retains cancel_delayed_work_sync() because it is also used for the CC enable/disable toggle path where the work must remain re-schedulable.
Detalles técnicos trazas, registros y código del informe original
cpu0 cpu1
mep_delete_implementation()
cancel_delayed_work_sync(ccm_rx_dwork);
br_cfm_frame_rx()
// peer_mep still in hlist
if (peer_mep->ccm_defect)
ccm_rx_timer_start()
queue_delayed_work(ccm_rx_dwork)
hlist_del_rcu(&peer_mep->head);
kfree_rcu(peer_mep, rcu);
ccm_rx_work_expired()
// on freed peer_mepCVSS
- 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: 0.10%
- Percentil entre todas las CVEs puntuadas: 1
- Fecha de la puntuación: 5/10/2026
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.
- Explotación
T1068Exploitation for Privilege Escalationprivilege escalation85 %
Vulnerabilidad de condición de carrera en kernel Linux (CWE-362) con acceso local y privilegios de usuario (AV:L, PR:L). Permite corrupción de memoria que facilita escalada de privilegios al explotar la race condition en la eliminación de peer MEP.
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
Tecnologías afectadas (1)
CWE
- CWE-362
Referencias
JSON original (NVD)
Mostrar
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbridge: cfm: Fix race condition in peer_mep deletion\n\nWhen a peer MEP is being deleted, cancel_delayed_work_sync() is called\non ccm_rx_dwork before freeing. However, br_cfm_frame_rx() runs in\nsoftirq context under rcu_read_lock (without RTNL) and can re-schedule\nccm_rx_dwork via ccm_rx_timer_start() between cancel_delayed_work_sync()\nreturning and kfree_rcu() being called.\n\nThe following is a simple race scenario:\n\n cpu0 cpu1\n\nmep_delete_implementation()\n cancel_delayed_work_sync(ccm_rx_dwork);\n br_cfm_frame_rx()\n // peer_mep still in hlist\n if (peer_mep->ccm_defect)\n ccm_rx_timer_start()\n queue_delayed_work(ccm_rx_dwork)\n hlist_del_rcu(&peer_mep->head);\n kfree_rcu(peer_mep, rcu);\n ccm_rx_work_expired()\n // on freed peer_mep\n\nTo prevent this, cancel_delayed_work_sync() is replaced with\ndisable_delayed_work_sync() in both peer MEP deletion paths, so\nthat subsequent queue_delayed_work() calls from br_cfm_frame_rx()\nare silently rejected.\n\nThe cc_peer_disable() helper retains cancel_delayed_work_sync()\nbecause it is also used for the CC enable/disable toggle path where\nthe work must remain re-schedulable."
},
{
"lang": "es",
"value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad:\n\nbridge: cfm: Corrección de condición de carrera en la eliminación de peer_mep\n\nCuando se está eliminando un MEP par, se llama a cancel_delayed_work_sync() en ccm_rx_dwork antes de la liberación. Sin embargo, br_cfm_frame_rx() se ejecuta en contexto de softirq bajo rcu_read_lock (sin RTNL) y puede reprogramar ccm_rx_dwork a través de ccm_rx_timer_start() entre el retorno de cancel_delayed_work_sync() y la llamada a kfree_rcu().\n\nEl siguiente es un escenario de condición de carrera simple:\n\n cpu0 cpu1\n\nmep_delete_implementation()\n cancel_delayed_work_sync(ccm_rx_dwork);\n br_cfm_frame_rx()\n // peer_mep todavía en hlist\n if (peer_mep->ccm_defect)\n ccm_rx_timer_start()\n queue_delayed_work(ccm_rx_dwork)\n hlist_del_rcu(&peer_mep->head);\n kfree_rcu(peer_mep, rcu);\n ccm_rx_work_expired()\n // en peer_mep liberado\n\nPara evitar esto, cancel_delayed_work_sync() se reemplaza por disable_delayed_work_sync() en ambas rutas de eliminación de MEP par, de modo que las llamadas posteriores a queue_delayed_work() desde br_cfm_frame_rx() sean rechazadas silenciosamente.\n\nLa función auxiliar cc_peer_disable() mantiene cancel_delayed_work_sync() porque también se utiliza para la ruta de alternancia de habilitación/deshabilitación de CC donde el trabajo debe permanecer reprogramable."
}
],
"lastModified": "2026-06-17T10:21:29.580",
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