CVE-2025-40215

Full vulnerability record from the local CVENow database.

Description

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")). 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.

Severity

HIGH

CVSS score

7.8 (v3.1)

Vulnerability status

Deferred

Source identifier

416baaa9-dc9f-4396-8d5f-8c081fb06d67

Published

2025-12-04 13:15:48.473000

Last modified

2026-10-19 21:10:00.160000

View original CVE JSON

{
  "id": "CVE-2025-40215",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2025-12-04T13:15:48.473",
  "lastModified": "2026-10-19T21:10:00.160",
  "vulnStatus": "Deferred",
  "cveTags": [],
  "descriptions": [
    {
      "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."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nxfrm: eliminar x->tunnel a medida que eliminamos x\n\nLos túneles de respaldo ipcomp actualmente se eliminan (de las diversas listas y tablas hash) a medida que el último estado de usuario que necesitaba ese respaldo es destruido (no eliminado). Si una referencia a ese estado de usuario aún existe, el estado de respaldo permanecerá en las tablas hash/listas, lo que activará la ADVERTENCIA en xfrm_state_fini. Debido a esas referencias restantes, la corrección en el commit f75a2804da39 (“xfrm: destruir xfrm_state sincrónicamente en la ruta de salida de red”) no está completa.\n\nRecientemente corregimos una situación similar en TCP debido a la liberación diferida de skbs (commit 9b6412e6979f (“tcp: eliminar secpath al mismo tiempo que actualmente eliminamos dst”)). Esto también puede ocurrir debido al reensamblaje de IP: los skbs con un secpath permanecen en la cola de reensamblaje hasta la destrucción de netns. Si no podemos garantizar que las colas se vacíen para cuando se ejecute xfrm_state_fini, aún puede haber referencias a un xfrm_state (de usuario), impidiendo la eliminación oportuna del estado de respaldo correspondiente.\n\nEn lugar de perseguir cada instancia de skbs que contiene un secpath una por una, este parche corrige el problema directamente dentro de xfrm, al eliminar el estado de respaldo tan pronto como el último estado de usuario que dependía de él haya sido eliminado. La destrucción seguirá ocurriendo cuando se elimine la referencia final.\n\nSe requiere una clase lockdep separada para el estado de respaldo ya que vamos a bloquear x->tunnel mientras x está bloqueado."
    }
  ],
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "programFiles": [
            "include/net/xfrm.h",
            "net/ipv4/ipcomp.c",
            "net/ipv6/ipcomp6.c",
            "net/ipv6/xfrm6_tunnel.c",
            "net/xfrm/xfrm_ipcomp.c",
            "net/xfrm/xfrm_state.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "9d4139c76905833afcb77fe8ccc17f302a0eb9ab",
              "lessThan": "1b28a7fae0128fa140a7dccd995182ff6cd1c67b",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "9d4139c76905833afcb77fe8ccc17f302a0eb9ab",
              "lessThan": "4b2c17d0f9be8b58bb30468bc81a4b61c985b04e",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "9d4139c76905833afcb77fe8ccc17f302a0eb9ab",
              "lessThan": "0da961fa46da1b37ef868d9b603bd202136f8f8e",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "9d4139c76905833afcb77fe8ccc17f302a0eb9ab",
              "lessThan": "d0e0d1097118461463b76562c7ebaabaa5b90b13",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "9d4139c76905833afcb77fe8ccc17f302a0eb9ab",
              "lessThan": "dc3636912d41770466543623cb76e7b88fdb42c7",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "9d4139c76905833afcb77fe8ccc17f302a0eb9ab",
              "lessThan": "b441cf3f8c4b8576639d20c8eb4aa32917602ecd",
              "versionType": "git",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "programFiles": [
            "include/net/xfrm.h",
            "net/ipv4/ipcomp.c",
            "net/ipv6/ipcomp6.c",
            "net/ipv6/xfrm6_tunnel.c",
            "net/xfrm/xfrm_ipcomp.c",
            "net/xfrm/xfrm_state.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "2.6.29",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "2.6.29",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "5.10.248",
              "lessThanOrEqual": "5.10.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "5.15.198",
              "lessThanOrEqual": "5.15.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.1.160",
              "lessThanOrEqual": "6.1.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.6.120",
              "lessThanOrEqual": "6.6.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.12.62",
              "lessThanOrEqual": "6.12.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.16",
              "lessThanOrEqual": "*",
              "versionType": "original_commit_for_fix",
              "status": "unaffected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "attackVector": "LOCAL",
          "attackComplexity": "LOW",
          "privilegesRequired": "LOW",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "availabilityImpact": "HIGH"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.9
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-06-16T19:56:10.578142Z",
          "id": "CVE-2025-40215",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/0da961fa46da1b37ef868d9b603bd202136f8f8e",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/1b28a7fae0128fa140a7dccd995182ff6cd1c67b",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/4b2c17d0f9be8b58bb30468bc81a4b61c985b04e",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/b441cf3f8c4b8576639d20c8eb4aa32917602ecd",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/d0e0d1097118461463b76562c7ebaabaa5b90b13",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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    {
      "url": "https://git.kernel.org/stable/c/dc3636912d41770466543623cb76e7b88fdb42c7",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ]
}