CVE-2026-64543

Estado: RecibidaAlta (7.8)—

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

tipc: fix use-after-free of the discoverer in tipc_disc_rcv()

bearer_disable() frees b->disc with tipc_disc_delete()'s plain kfree(), but tipc_disc_rcv() still dereferences b->disc in RX softirq under rcu_read_lock() (tipc_udp_recv -> tipc_rcv -> tipc_disc_rcv).

L2 bearers are safe thanks to the synchronize_net() in tipc_disable_l2_media(), but the UDP bearer defers that call to the cleanup_bearer() workqueue, so the discoverer is freed with no grace period:

The bearer is freed with kfree_rcu(); free the discoverer the same way. Add an rcu_head to struct tipc_discoverer and free it and its skb from an RCU callback.

Leer descripción completaMostrar menos

Because the RCU callback (tipc_disc_free_rcu) lives in module text, a call_rcu() that is still pending when the tipc module is unloaded would invoke a freed function. Add an rcu_barrier() to tipc_exit() after the bearer subsystem has been torn down, so all pending discoverer callbacks have run before the module text goes away.

Reachable from an unprivileged user namespace: the TIPCv2 genl family is netnsok and its bearer commands have no GENL_ADMIN_PERM. Needs CONFIG_TIPC and CONFIG_TIPC_MEDIA_UDP.

Detalles técnicos trazas, registros y código del informe original

 BUG: KASAN: slab-use-after-free in tipc_disc_rcv (net/tipc/discover.c:149)
 Read of size 8 at addr ffff88802348b728 by task poc_tipc/184
 <IRQ>
  tipc_disc_rcv (net/tipc/discover.c:149)
  tipc_rcv (net/tipc/node.c:2126)
  tipc_udp_recv (net/tipc/udp_media.c:391)
  udp_rcv (net/ipv4/udp.c:2643)
  ip_local_deliver_finish (net/ipv4/ip_input.c:241)
 </IRQ>
 Freed by task 181:
  kfree (mm/slub.c:6565)
  bearer_disable (net/tipc/bearer.c:418)
  tipc_nl_bearer_disable (net/tipc/bearer.c:1001)

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: 0.13%
Percentil entre todas las CVEs puntuadas: 2
Fecha de la puntuación: 5/10/2026

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 escalation85 %
Impacto principalT1499.004 Application or System Exploitationimpact75 %
Impacto secundarioT1005 Data from Local Systemcollection60 %

Vulnerabilidad de use-after-free en kernel Linux explotable desde espacio de usuario sin privilegios (PR:L en namespace) causando DoS por corrupción de memoria y lectura de datos sensibles del kernel.

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 Program Filter Network Traffic Execution Prevention Application Isolation and Sandboxing Exploit Protection Update Software

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-2026-64543",
  "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"
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        "exploitabilityScore": 1.8
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  "published": "2026-07-27T21:17:06.850",
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      "url": "https://git.kernel.org/stable/c/1579342d71133da7f00daa02c75cebec7372097b",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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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\ntipc: fix use-after-free of the discoverer in tipc_disc_rcv()\n\nbearer_disable() frees b->disc with tipc_disc_delete()'s plain kfree(),\nbut tipc_disc_rcv() still dereferences b->disc in RX softirq under\nrcu_read_lock() (tipc_udp_recv -> tipc_rcv -> tipc_disc_rcv).\n\nL2 bearers are safe thanks to the synchronize_net() in\ntipc_disable_l2_media(), but the UDP bearer defers that call to the\ncleanup_bearer() workqueue, so the discoverer is freed with no grace\nperiod:\n\n BUG: KASAN: slab-use-after-free in tipc_disc_rcv (net/tipc/discover.c:149)\n Read of size 8 at addr ffff88802348b728 by task poc_tipc/184\n <IRQ>\n  tipc_disc_rcv (net/tipc/discover.c:149)\n  tipc_rcv (net/tipc/node.c:2126)\n  tipc_udp_recv (net/tipc/udp_media.c:391)\n  udp_rcv (net/ipv4/udp.c:2643)\n  ip_local_deliver_finish (net/ipv4/ip_input.c:241)\n </IRQ>\n Freed by task 181:\n  kfree (mm/slub.c:6565)\n  bearer_disable (net/tipc/bearer.c:418)\n  tipc_nl_bearer_disable (net/tipc/bearer.c:1001)\n\nThe bearer is freed with kfree_rcu(); free the discoverer the same way.\nAdd an rcu_head to struct tipc_discoverer and free it and its skb from an\nRCU callback.\n\nBecause the RCU callback (tipc_disc_free_rcu) lives in module text, a\ncall_rcu() that is still pending when the tipc module is unloaded would\ninvoke a freed function. Add an rcu_barrier() to tipc_exit() after the\nbearer subsystem has been torn down, so all pending discoverer callbacks\nhave run before the module text goes away.\n\nReachable from an unprivileged user namespace: the TIPCv2 genl family is\nnetnsok and its bearer commands have no GENL_ADMIN_PERM. Needs CONFIG_TIPC\nand CONFIG_TIPC_MEDIA_UDP."
    }
  ],
  "lastModified": "2026-08-19T17:20:15.650",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}