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CVE-2025-40297

Estado: AplazadaAlta (7.8)—

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

net: bridge: fix use-after-free due to MST port state bypass

syzbot reported[1] a use-after-free when deleting an expired fdb. It is due to a race condition between learning still happening and a port being deleted, after all its fdbs have been flushed.

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The port's state has been toggled to disabled so no learning should happen at that time, but if we have MST enabled, it will bypass the port's state, that together with VLAN filtering disabled can lead to fdb learning at a time when it shouldn't happen while the port is being deleted. VLAN filtering must be disabled because we flush the port VLANs when it's being deleted which will stop learning. This fix adds a check for the port's vlan group which is initialized to NULL when the port is getting deleted, that avoids the port state bypass. When MST is enabled there would be a minimal new overhead in the fast-path because the port's vlan group pointer is cache-hot.

[1] https://syzkaller.appspot.com/bug?extid=dd280197f0f7ab3917be

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 local (AV:L) con privilegios limitados (PR:L) que causa use-after-free en el kernel Linux. Permite escalada de privilegios (T1068) explotando la carrera de condiciones. Los impactos incluyen negación de servicio por corrupción de memoria y manipulación potencial de datos de puente de

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 ProgramRestrict File and Directory PermissionsRemote Data StorageFilter Network TrafficExecution PreventionEncrypt Sensitive Information

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-2025-40297",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.8,
          "attackVector": "LOCAL",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 1.8
      }
    ]
  },
  "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": "ec7328b59176227216c461601c6bd0e922232a9b",
              "lessThan": "e19085b2a86addccff33ab8536fc67ebd9d52198",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "ec7328b59176227216c461601c6bd0e922232a9b",
              "lessThan": "3b60ce334c1ce8b3fad7e02dcd5ed9f6646477c8",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "ec7328b59176227216c461601c6bd0e922232a9b",
              "lessThan": "bf3843183bc3158e5821b46f330c438ae9bd6ddb",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "ec7328b59176227216c461601c6bd0e922232a9b",
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              "versionType": "git"
            },
            {
              "status": "affected",
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              "lessThan": "8dca36978aa80bab9d4da130c211db75c9e00048",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "net/bridge/br_forward.c",
            "net/bridge/br_input.c",
            "net/bridge/br_private.h"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.18"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "5.18",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.1.159",
              "versionType": "semver",
              "lessThanOrEqual": "6.1.*"
            },
            {
              "status": "unaffected",
              "version": "6.6.117",
              "versionType": "semver",
              "lessThanOrEqual": "6.6.*"
            },
            {
              "status": "unaffected",
              "version": "6.12.58",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.17.8",
              "versionType": "semver",
              "lessThanOrEqual": "6.17.*"
            },
            {
              "status": "unaffected",
              "version": "6.18",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "net/bridge/br_forward.c",
            "net/bridge/br_input.c",
            "net/bridge/br_private.h"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2025-12-08T01:16:01.813",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/3b60ce334c1ce8b3fad7e02dcd5ed9f6646477c8",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/8dca36978aa80bab9d4da130c211db75c9e00048",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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    {
      "url": "https://git.kernel.org/stable/c/991fbe1680cd41a5f97c92cd3a3496315df36e4b",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/bf3843183bc3158e5821b46f330c438ae9bd6ddb",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/e19085b2a86addccff33ab8536fc67ebd9d52198",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Deferred",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: bridge: fix use-after-free due to MST port state bypass\n\nsyzbot reported[1] a use-after-free when deleting an expired fdb. It is\ndue to a race condition between learning still happening and a port being\ndeleted, after all its fdbs have been flushed. The port's state has been\ntoggled to disabled so no learning should happen at that time, but if we\nhave MST enabled, it will bypass the port's state, that together with VLAN\nfiltering disabled can lead to fdb learning at a time when it shouldn't\nhappen while the port is being deleted. VLAN filtering must be disabled\nbecause we flush the port VLANs when it's being deleted which will stop\nlearning. This fix adds a check for the port's vlan group which is\ninitialized to NULL when the port is getting deleted, that avoids the port\nstate bypass. When MST is enabled there would be a minimal new overhead\nin the fast-path because the port's vlan group pointer is cache-hot.\n\n[1] https://syzkaller.appspot.com/bug?extid=dd280197f0f7ab3917be"
    }
  ],
  "lastModified": "2026-07-30T06:24:27.157",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}