CVE-2026-68335

Estado: RecibidaAlta (7.8)—

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

rds: drop incoming messages that cross network namespace boundaries

rds_find_bound() looks up the destination socket using a global rhashtable keyed solely on (addr, port, scope_id). Network namespaces are not part of the key, so a sender in netns A can deliver an incoming message (inc) to a socket that lives in a different netns B.

When this happens, inc->i_conn points to an rds_connection whose c_net is netns A, but the receiving rs lives in netns B.

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Once the child process that created netns A exits, cleanup_net() calls rds_loop_exit_net() -> rds_loop_kill_conns() -> rds_conn_destroy(), freeing that connection. If the survivor socket in netns B still holds the inc, any subsequent dereference of inc->i_conn is a use-after-free.

The bug is reachable from unprivileged user namespaces (CLONE_NEWUSER + CLONE_NEWNET), available since Linux 3.8.

Fix this by rejecting the delivery in rds_recv_incoming() when the socket returned by rds_find_bound() belongs to a different network namespace than the connection that carried the message. Use the existing rds_conn_net() / sock_net() helpers and net_eq() for the comparison.

Detalles técnicos trazas, registros y código del informe original

There are two dangerous sites in rds_clear_recv_queue():
  1. inc->i_conn->c_lcong (offset 88 of freed rds_connection, size 200)
     read via rds_recv_rcvbuf_delta() -- confirmed by KASAN.
  2. inc->i_conn->c_trans->inc_free(inc) (function pointer at offset 80)
     called via rds_inc_put() when the inc refcount reaches zero -- same
     race window, potential call-through-freed-object primitive.

CVSS

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: 0.14%
Percentil entre todas las CVEs puntuadas: 3
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.

ExplotaciónT1068 Exploitation for Privilege Escalationprivilege escalation90 %
Impacto principalT1499.004 Application or System Exploitationimpact75 %
Impacto secundarioT1047 Windows Management Instrumentationexecution60 %

Escalada local de privilegios en kernel Linux vía namespace crossing (AV:L/PR:L). Use-after-free explotable desde espacios de usuario no privilegiados (CLONE_NEWUSER). Causa DoS e impacto en integridad del sistema.

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

Execution Prevention User Account Management Threat Intelligence Program Privileged Account Management Filter Network Traffic Behavior Prevention on Endpoint

Tecnologías afectadas (1)

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

Linux — Linux Kernel^AI

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-68335",
  "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",
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          "confidentialityImpact": "HIGH"
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  "published": "2026-08-10T13:20:23.863",
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nrds: drop incoming messages that cross network namespace boundaries\n\nrds_find_bound() looks up the destination socket using a global\nrhashtable keyed solely on (addr, port, scope_id).  Network namespaces\nare not part of the key, so a sender in netns A can deliver an incoming\nmessage (inc) to a socket that lives in a different netns B.\n\nWhen this happens, inc->i_conn points to an rds_connection whose c_net\nis netns A, but the receiving rs lives in netns B.  Once the child\nprocess that created netns A exits, cleanup_net() calls\nrds_loop_exit_net() -> rds_loop_kill_conns() -> rds_conn_destroy(),\nfreeing that connection.  If the survivor socket in netns B still holds\nthe inc, any subsequent dereference of inc->i_conn is a use-after-free.\n\nThere are two dangerous sites in rds_clear_recv_queue():\n  1. inc->i_conn->c_lcong (offset 88 of freed rds_connection, size 200)\n     read via rds_recv_rcvbuf_delta() -- confirmed by KASAN.\n  2. inc->i_conn->c_trans->inc_free(inc) (function pointer at offset 80)\n     called via rds_inc_put() when the inc refcount reaches zero -- same\n     race window, potential call-through-freed-object primitive.\n\nThe bug is reachable from unprivileged user namespaces\n(CLONE_NEWUSER + CLONE_NEWNET), available since Linux 3.8.\n\nFix this by rejecting the delivery in rds_recv_incoming() when the\nsocket returned by rds_find_bound() belongs to a different network\nnamespace than the connection that carried the message.  Use the\nexisting rds_conn_net() / sock_net() helpers and net_eq() for the\ncomparison."
    }
  ],
  "lastModified": "2026-08-19T17:20:43.490",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}