CVE-2025-40215

Estado: AplazadaAlta (7.8)—

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

xfrm: delete x->tunnel as we delete x

The ipcomp fallback tunnels currently get deleted (from the various lists and hashtables) as the last user state that needed that fallback is destroyed (not deleted). If a reference to that user state still exists, the fallback state will remain on the hashtables/lists, triggering the WARN in xfrm_state_fini. Because of those remaining references, the fix in commit f75a2804da39 ("xfrm: destroy xfrm_state synchronously on net exit path") is not complete.

We recently fixed one such situation in TCP due to defered freeing of skbs (commit 9b6412e6979f ("tcp: drop secpath at the same time as we currently drop dst")).

Leer descripción completaMostrar menos

This can also happen due to IP reassembly: skbs with a secpath remain on the reassembly queue until netns destruction. If we can't guarantee that the queues are flushed by the time xfrm_state_fini runs, there may still be references to a (user) xfrm_state, preventing the timely deletion of the corresponding fallback state.

Instead of chasing each instance of skbs holding a secpath one by one, this patch fixes the issue directly within xfrm, by deleting the fallback state as soon as the last user state depending on it has been deleted. Destruction will still happen when the final reference is dropped.

A separate lockdep class for the fallback state is required since we're going to lock x->tunnel while x is locked.

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: 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 escalation75 %
Impacto principalT1499.004 Application or System Exploitationimpact60 %

Vulnerabilidad local de escalada de privilegios en kernel Linux (AV:L, PR:L) que permite DoS por condición de carrera en xfrm_state_fini al no liberar estados fallback correctamente.

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-2025-40215",
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  "published": "2025-12-04T13:15:48.473",
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    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: delete x->tunnel as we delete x\n\nThe ipcomp fallback tunnels currently get deleted (from the various\nlists and hashtables) as the last user state that needed that fallback\nis destroyed (not deleted). If a reference to that user state still\nexists, the fallback state will remain on the hashtables/lists,\ntriggering the WARN in xfrm_state_fini. Because of those remaining\nreferences, the fix in commit f75a2804da39 (\"xfrm: destroy xfrm_state\nsynchronously on net exit path\") is not complete.\n\nWe recently fixed one such situation in TCP due to defered freeing of\nskbs (commit 9b6412e6979f (\"tcp: drop secpath at the same time as we\ncurrently drop dst\")). This can also happen due to IP reassembly: skbs\nwith a secpath remain on the reassembly queue until netns\ndestruction. If we can't guarantee that the queues are flushed by the\ntime xfrm_state_fini runs, there may still be references to a (user)\nxfrm_state, preventing the timely deletion of the corresponding\nfallback state.\n\nInstead of chasing each instance of skbs holding a secpath one by one,\nthis patch fixes the issue directly within xfrm, by deleting the\nfallback state as soon as the last user state depending on it has been\ndeleted. Destruction will still happen when the final reference is\ndropped.\n\nA separate lockdep class for the fallback state is required since\nwe're going to lock x->tunnel while x is locked."
    }
  ],
  "lastModified": "2026-07-30T06:24:18.487",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}