CVE-2026-89479

Estado: RecibidaCrítica (9.8)—

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

sctp: stop processing a packet once its association is deleted

sctp_endpoint_bh_rcv() looks the association up only when chunk->asoc is NULL, and caches the result in chunk->asoc and chunk->transport without taking a reference.

A packet that matches no association is handed to the endpoint, so a peer can bundle COOKIE ECHO, SHUTDOWN and SHUTDOWN ACK in one packet. The COOKIE ECHO creates the association, the SHUTDOWN chunk caches it, and with the outqueue empty the SHUTDOWN ACK reaches sctp_sf_do_9_2_final(), so the association and its transports are freed.

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The endpoint loop has no counterpart to the asoc->base.dead check in sctp_assoc_bh_rcv(). The next chunk writes to last_time_heard in the freed transport and is then passed to sctp_do_sm() with the freed association. The transport is freed through RCU, so this needs the packet to come off the socket backlog, where the loop runs in task context.

The endpoint loop cannot do the same check: it holds no reference on the association, so reading asoc->base.dead would itself be a use-after-free. Mark the packet for discard in the command interpreter, just before it deletes the association. That is also before sctp_inq_free() releases the chunk on the association receive path.

sctp_sf_do_5_2_4_dupcook() issues SCTP_CMD_DELETE_TCB for the temporary association, while the one the packet belongs to stays alive. A restarting peer can bundle DATA behind its COOKIE ECHO, so compare against chunk->asoc and leave that case alone.

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Puntuación base: 9.8

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.50%
Percentil entre todas las CVEs puntuadas: 41
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.

ExplotaciónT1190 Exploit Public-Facing Applicationinitial access85 %
Impacto principalT1068 Exploitation for Privilege Escalationprivilege escalation75 %
Impacto secundarioT1499.004 Application or System Exploitationimpact70 %

Vulnerabilidad remota en kernel Linux (AV:N, PR:N, UI:N) explotable sin autenticación. Permite use-after-free en SCTP causando corrupción de memoria y acceso a estructuras liberadas, logrando escalada de privilegios o denegación de servicio.

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

Filter Network Traffic Application Isolation and Sandboxing Exploit Protection Update Software Vulnerability Scanning Threat Intelligence Program

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-2026-89479",
  "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
      }
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      "affectedData": [
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          "product": "Linux",
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      ]
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  ],
  "published": "2026-09-11T20:19:29.337",
  "references": [
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      "url": "https://git.kernel.org/stable/c/09c3b193a3e8fe53e1f416e2f8e3283d2a785405",
      "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\nsctp: stop processing a packet once its association is deleted\n\nsctp_endpoint_bh_rcv() looks the association up only when chunk->asoc is\nNULL, and caches the result in chunk->asoc and chunk->transport without\ntaking a reference.\n\nA packet that matches no association is handed to the endpoint, so a peer\ncan bundle COOKIE ECHO, SHUTDOWN and SHUTDOWN ACK in one packet. The\nCOOKIE ECHO creates the association, the SHUTDOWN chunk caches it, and\nwith the outqueue empty the SHUTDOWN ACK reaches sctp_sf_do_9_2_final(),\nso the association and its transports are freed.\n\nThe endpoint loop has no counterpart to the asoc->base.dead check in\nsctp_assoc_bh_rcv(). The next chunk writes to last_time_heard in the freed\ntransport and is then passed to sctp_do_sm() with the freed association.\nThe transport is freed through RCU, so this needs the packet to come off\nthe socket backlog, where the loop runs in task context.\n\nThe endpoint loop cannot do the same check: it holds no reference on the\nassociation, so reading asoc->base.dead would itself be a use-after-free.\nMark the packet for discard in the command interpreter, just before it\ndeletes the association. That is also before sctp_inq_free() releases the\nchunk on the association receive path.\n\nsctp_sf_do_5_2_4_dupcook() issues SCTP_CMD_DELETE_TCB for the temporary\nassociation, while the one the packet belongs to stays alive. A restarting\npeer can bundle DATA behind its COOKIE ECHO, so compare against\nchunk->asoc and leave that case alone."
    }
  ],
  "lastModified": "2026-09-14T13:19:04.457",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}