CVE-2026-53043

Estado: AnalizadaCrítica (9.1)—

In the Linux kernel, the following vulnerability has been resolved:

ocfs2/dlm: validate qr_numregions in dlm_match_regions()

Patch series "ocfs2/dlm: fix two bugs in dlm_match_regions()".

In dlm_match_regions(), the qr_numregions field from a DLM_QUERY_REGION network message is used to drive loops over the qr_regions buffer without sufficient validation. This series fixes two issues:

This patch (of 2):

The qr_numregions field from a DLM_QUERY_REGION network message is used directly as loop bounds in dlm_match_regions() without checking against O2NM_MAX_REGIONS. Since qr_regions is sized for at most O2NM_MAX_REGIONS (32) entries, a crafted message with qr_numregions > 32 causes out-of-bounds reads past the qr_regions buffer.

Leer descripción completaMostrar menos

Add a bounds check for qr_numregions before entering the loops.

Detalles técnicos trazas, registros y código del informe original

- Patch 1 adds a bounds check to reject messages where qr_numregions
  exceeds O2NM_MAX_REGIONS. The o2net layer only validates message
  byte length; it does not constrain field values, so a crafted message
  can set qr_numregions up to 255 and trigger out-of-bounds reads past
  the 1024-byte qr_regions buffer.

- Patch 2 fixes an off-by-one in the local-vs-remote comparison loop,
  which uses '<=' instead of '<', reading one entry past the valid range
  even when qr_numregions is within bounds.

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Puntuación base: 9.1

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.73%
Percentil entre todas las CVEs puntuadas: 53
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.

ExplotaciónT1190 Exploit Public-Facing Applicationinitial access85 %
Impacto principalT1005 Data from Local Systemcollection90 %
Impacto secundarioT1499.004 Application or System Exploitationimpact75 %

Vulnerabilidad de lectura fuera de límites (CWE-787) en kernel Linux explotable remotamente sin autenticación (AV:N/PR:N) mediante mensaje DLM_QUERY_REGION manipulado. Acceso a datos sensibles del kernel y potencial DoS por lectura descontrolada.

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

Filter Network Traffic Vulnerability Scanning Privileged Account Management Network Segmentation Limit Access to Resource Over Network Application Isolation and Sandboxing

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

CWE-787

Referencias

JSON original (NVD)

Mostrar

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      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nocfs2/dlm: validate qr_numregions in dlm_match_regions()\n\nPatch series \"ocfs2/dlm: fix two bugs in dlm_match_regions()\".\n\nIn dlm_match_regions(), the qr_numregions field from a DLM_QUERY_REGION\nnetwork message is used to drive loops over the qr_regions buffer without\nsufficient validation.  This series fixes two issues:\n\n- Patch 1 adds a bounds check to reject messages where qr_numregions\n  exceeds O2NM_MAX_REGIONS. The o2net layer only validates message\n  byte length; it does not constrain field values, so a crafted message\n  can set qr_numregions up to 255 and trigger out-of-bounds reads past\n  the 1024-byte qr_regions buffer.\n\n- Patch 2 fixes an off-by-one in the local-vs-remote comparison loop,\n  which uses '<=' instead of '<', reading one entry past the valid range\n  even when qr_numregions is within bounds.\n\n\nThis patch (of 2):\n\nThe qr_numregions field from a DLM_QUERY_REGION network message is used\ndirectly as loop bounds in dlm_match_regions() without checking against\nO2NM_MAX_REGIONS.  Since qr_regions is sized for at most O2NM_MAX_REGIONS\n(32) entries, a crafted message with qr_numregions > 32 causes\nout-of-bounds reads past the qr_regions buffer.\n\nAdd a bounds check for qr_numregions before entering the loops."
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