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CVE-2026-80926

Estado: RecibidaCrítica (9.8)—

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

ksmbd: fix use-after-free in oplock break notification

smb2_oplock_break_noti() reads opinfo->conn without any lock and dereferences it after two allocations which may sleep. When the durable handle owning the oplock is disconnected, session_fd_check() clears opinfo->conn and drops its conn reference under ci->m_lock, and the last ksmbd_conn_put() frees the connection. A break triggered by another connection that races with the teardown can then resurrect the freed connection: ksmbd_conn_get() is a plain atomic_inc, and the queued break work later dereferences the stale conn via ksmbd_conn_write(), a use-after-free reachable by any authenticated client holding a durable batch oplock.

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Thread the caller's inode into the notification path instead of taking a new reference on it. Every caller of oplock_break() already holds a live ksmbd_file (or an explicit ksmbd_inode_lookup_lock() reference, in the parent lease break paths) on the inode that owns the break target's oplock list, so ci cannot be freed during the call, and its lock can be taken without dereferencing opinfo->o_fp, which a concurrent close may free. Select and pin the connection under ci->m_lock, the same lock session_fd_check() and ksmbd_reopen_durable_fd() use to update opinfo->conn, so a concurrent detach either loses the race to the clear or keeps the connection alive until the notification work releases it. Transfer the reference to the work item and release it on allocation failures.

CVSS

Probabilidad de explotación (EPSS)

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.

Vulnerabilidad de use-after-free en ksmbd accesible por cliente autenticado en red (AV:N, PR:N). Permite escalada de privilegios y lectura de datos de kernel mediante dereference de conexión liberada.

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

Application Isolation and SandboxingExploit ProtectionUpdate SoftwareVulnerability ScanningThreat Intelligence ProgramPrivileged Account Management

Tecnologías afectadas (1)

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

Linux — Linux KernelAI

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-80926",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 9.8,
          "attackVector": "NETWORK",
          "baseSeverity": "CRITICAL",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 3.9
      }
    ]
  },
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "945a86b21b40fb17183f5b27461baa6f03e2467f",
              "lessThan": "892f643b141aee3f7aa7c0fc61ddcb55c59f1996",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "1ff58dcfcab434ebb51649da33774fbb8e1f7b67",
              "lessThan": "5de0527f782430b1109a447646e32033ad018a6a",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "e735dbd489e3ea02be78dba991056fe1138be51e",
              "lessThan": "c8279ae8df68cce9cd3b785e85f7a86c80a46e78",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "b003086d76968298f22e7cf62239833b5a3a06b1",
              "lessThan": "8cc98db4fc590e6c7d9db6529320982ee16c5d1d",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "b003086d76968298f22e7cf62239833b5a3a06b1",
              "lessThan": "0e753899627b5e28a9fea8bca98262a6f65a2452",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "75e33deda658c1ab3a9336cbdb1436536f9b3660",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "6.6.143",
              "lessThan": "6.6.158",
              "versionType": "semver"
            },
            {
              "status": "affected",
              "version": "6.12.94",
              "lessThan": "6.12.111",
              "versionType": "semver"
            },
            {
              "status": "affected",
              "version": "6.18.36",
              "lessThan": "6.18.51",
              "versionType": "semver"
            },
            {
              "status": "affected",
              "version": "7.0.13",
              "lessThan": "7.1",
              "versionType": "semver"
            }
          ],
          "programFiles": [
            "fs/smb/server/oplock.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.1"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "7.1",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.6.158",
              "versionType": "semver",
              "lessThanOrEqual": "6.6.*"
            },
            {
              "status": "unaffected",
              "version": "6.12.111",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.18.51",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.2.5",
              "versionType": "semver",
              "lessThanOrEqual": "7.2.*"
            },
            {
              "status": "unaffected",
              "version": "7.3-rc2",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "fs/smb/server/oplock.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-09-11T20:18:56.257",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/0e753899627b5e28a9fea8bca98262a6f65a2452",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/5de0527f782430b1109a447646e32033ad018a6a",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/892f643b141aee3f7aa7c0fc61ddcb55c59f1996",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/8cc98db4fc590e6c7d9db6529320982ee16c5d1d",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/c8279ae8df68cce9cd3b785e85f7a86c80a46e78",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix use-after-free in oplock break notification\n\nsmb2_oplock_break_noti() reads opinfo->conn without any lock and\ndereferences it after two allocations which may sleep.  When the\ndurable handle owning the oplock is disconnected, session_fd_check()\nclears opinfo->conn and drops its conn reference under ci->m_lock, and\nthe last ksmbd_conn_put() frees the connection.  A break triggered by\nanother connection that races with the teardown can then resurrect the\nfreed connection: ksmbd_conn_get() is a plain atomic_inc, and the\nqueued break work later dereferences the stale conn via\nksmbd_conn_write(), a use-after-free reachable by any authenticated\nclient holding a durable batch oplock.\n\nThread the caller's inode into the notification path instead of taking\na new reference on it.  Every caller of oplock_break() already holds a\nlive ksmbd_file (or an explicit ksmbd_inode_lookup_lock() reference,\nin the parent lease break paths) on the inode that owns the break\ntarget's oplock list, so ci cannot be freed during the call, and its\nlock can be taken without dereferencing opinfo->o_fp, which a\nconcurrent close may free.  Select and pin the connection under\nci->m_lock, the same lock session_fd_check() and\nksmbd_reopen_durable_fd() use to update opinfo->conn, so a concurrent\ndetach either loses the race to the clear or keeps the connection\nalive until the notification work releases it.  Transfer the reference\nto the work item and release it on allocation failures."
    }
  ],
  "lastModified": "2026-10-03T11:17:40.913",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}