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CVE-2026-68323

Estado: RecibidaAlta (7.8)—

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

tipc: serialize udp bearer replicast list updates

tipc_udp_rcast_add() and cleanup_bearer() both update ub->rcast.list with list_add_rcu() / list_del_rcu(), but nothing serializes them. The add runs from the encap receive softirq (via tipc_udp_rcast_disc()) without rtnl_lock(), so it can race the cleanup delete and corrupt the list:

The bearer can be enabled from an unprivileged user namespace, as the TIPCv2 generic-netlink ops carry no GENL_ADMIN_PERM.

Add a spinlock to struct udp_bearer and take it around the list_add_rcu() in tipc_udp_rcast_add() and the list_del_rcu() loop in cleanup_bearer() so the two writers can no longer corrupt the list.

Leer descripción completaMostrar menos

Reject a duplicate peer under the same lock before allocating, and remove tipc_udp_is_known_peer(). The old lockless pre-check in tipc_udp_rcast_disc() was racy: two softirqs discovering the same peer could both find it absent and add it twice.

cleanup_bearer() runs from a workqueue after tipc_udp_disable() clears the bearer's up bit, so an encap softirq can still reach tipc_udp_rcast_add() and add a peer after cleanup_bearer() has already emptied the list, leaking that entry when the bearer is freed. Mark the bearer disabled under rcast_lock once the list is emptied and refuse further additions.

Detalles técnicos trazas, registros y código del informe original
  list_del corruption. prev->next should be ffff8880298d7ab8,
    but was ffff88802449ad38. (prev=ffff888027e3ec98)
  kernel BUG at lib/list_debug.c:62!
  RIP: __list_del_entry_valid_or_report+0x17a/0x200
  Workqueue: events cleanup_bearer
  Call Trace:
   cleanup_bearer (net/tipc/udp_media.c:811)
   process_one_work (kernel/workqueue.c:3302)
   worker_thread (kernel/workqueue.c:3466)

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 escalada local (AV:L, PR:L) en kernel Linux. Corrupción de lista enlazada (DoS/memoria) y manipulación de estructura de datos explotable desde namespace sin privilegios.

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-2026-68323",
  "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": "ef20cd4dd1633987bcf46ac34ace2c8af212361f",
              "lessThan": "d70c81001df9320d3445e664428a1d408b5ba896",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "ef20cd4dd1633987bcf46ac34ace2c8af212361f",
              "lessThan": "350e592ff4e30e48ffb55e142d11a73e63f4869c",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "net/tipc/udp_media.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.9"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "4.9",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "7.1.6",
              "versionType": "semver",
              "lessThanOrEqual": "7.1.*"
            },
            {
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "net/tipc/udp_media.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-08-10T13:20:22.443",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/350e592ff4e30e48ffb55e142d11a73e63f4869c",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/d70c81001df9320d3445e664428a1d408b5ba896",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: serialize udp bearer replicast list updates\n\ntipc_udp_rcast_add() and cleanup_bearer() both update ub->rcast.list with\nlist_add_rcu() / list_del_rcu(), but nothing serializes them. The add runs\nfrom the encap receive softirq (via tipc_udp_rcast_disc()) without\nrtnl_lock(), so it can race the cleanup delete and corrupt the list:\n\n  list_del corruption. prev->next should be ffff8880298d7ab8,\n    but was ffff88802449ad38. (prev=ffff888027e3ec98)\n  kernel BUG at lib/list_debug.c:62!\n  RIP: __list_del_entry_valid_or_report+0x17a/0x200\n  Workqueue: events cleanup_bearer\n  Call Trace:\n   cleanup_bearer (net/tipc/udp_media.c:811)\n   process_one_work (kernel/workqueue.c:3302)\n   worker_thread (kernel/workqueue.c:3466)\n\nThe bearer can be enabled from an unprivileged user namespace, as the\nTIPCv2 generic-netlink ops carry no GENL_ADMIN_PERM.\n\nAdd a spinlock to struct udp_bearer and take it around the list_add_rcu()\nin tipc_udp_rcast_add() and the list_del_rcu() loop in cleanup_bearer() so\nthe two writers can no longer corrupt the list.\n\nReject a duplicate peer under the same lock before allocating, and remove\ntipc_udp_is_known_peer(). The old lockless pre-check in\ntipc_udp_rcast_disc() was racy: two softirqs discovering the same peer\ncould both find it absent and add it twice.\n\ncleanup_bearer() runs from a workqueue after tipc_udp_disable() clears the\nbearer's up bit, so an encap softirq can still reach tipc_udp_rcast_add()\nand add a peer after cleanup_bearer() has already emptied the list, leaking\nthat entry when the bearer is freed. Mark the bearer disabled under\nrcast_lock once the list is emptied and refuse further additions."
    }
  ],
  "lastModified": "2026-08-17T05:18:35.267",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}