CVE-2025-40215 (GCVE-0-2025-40215)

Vulnerability from cvelistv5 – Published: 2025-12-04 12:38 – Updated: 2026-08-05 12:08
VLAI
Title
xfrm: delete x->tunnel as we delete x
Summary
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
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-06-16 19:56 UTC
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7061 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 9d4139c76905833afcb77fe8ccc17f302a0eb9ab , < 1b28a7fae0128fa140a7dccd995182ff6cd1c67b (git)
Affected: 9d4139c76905833afcb77fe8ccc17f302a0eb9ab , < 4b2c17d0f9be8b58bb30468bc81a4b61c985b04e (git)
Affected: 9d4139c76905833afcb77fe8ccc17f302a0eb9ab , < 0da961fa46da1b37ef868d9b603bd202136f8f8e (git)
Affected: 9d4139c76905833afcb77fe8ccc17f302a0eb9ab , < d0e0d1097118461463b76562c7ebaabaa5b90b13 (git)
Affected: 9d4139c76905833afcb77fe8ccc17f302a0eb9ab , < dc3636912d41770466543623cb76e7b88fdb42c7 (git)
Affected: 9d4139c76905833afcb77fe8ccc17f302a0eb9ab , < b441cf3f8c4b8576639d20c8eb4aa32917602ecd (git)
guessed Create a notification for this product.
Linux Linux Affected: 2.6.29
Unaffected: 0 , < 2.6.29 (semver)
Unaffected: 5.10.248 , ≤ 5.10.* (semver)
Unaffected: 5.15.198 , ≤ 5.15.* (semver)
Unaffected: 6.1.160 , ≤ 6.1.* (semver)
Unaffected: 6.6.120 , ≤ 6.6.* (semver)
Unaffected: 6.12.62 , ≤ 6.12.* (semver)
Unaffected: 6.16 , ≤ * (original_commit_for_fix)
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              "value": "AV:L - Triggering requires locally configuring an IPComp tunnel-mode SA via XFRM netlink and then tearing down the network namespace; a purely remote peer can pin the secpath reference but cannot create the SA or cause the netns teardown that frees the hash tables.\nAC:L - The attacker controls every element \u2014 SA creation, injecting the IPComp/fragmented packet that leaves an skb secpath reference outstanding, and the timing of namespace destruction \u2014 and the 30-second reassembly-queue window gives a large, reliable interval to groom the reclaimed kmalloc-64 bucket array and struct net.\nPR:L - XFRM state configuration is gated on netlink_net_capable(CAP_NET_ADMIN), which an unprivileged user obtains over their own namespace with `unshare -Urn`, and the ipcomp module autoloads via request_module() with no capability check.\nUI:N - The entire sequence \u2014 SA setup, packet injection, namespace exit \u2014 is performed by the attacker\u0027s own process with no action by any other user.\nS:U - The corrupted objects (xfrm hash tables, struct net, pernet data) and the vulnerable code are both kernel-resident, so impact stays within the kernel\u0027s security authority.\nC:H - The stale state is unlinked from already-freed memory, so its list/hlist traversal reads reclaimed slab contents and leaks kernel pointers into attacker-controllable objects, which is leverageable for arbitrary kernel memory disclosure.\nI:H - __xfrm_state_delete() performs list_del()/hlist_del_rcu() and net-\u003exfrm.state_num-- on a freed struct net and a freed 64-byte bucket array, writing heap pointers at controlled offsets into reclaimed slab objects \u2014 a use-after-free write primitive usable for control-flow hijack.\nA:H - The bug immediately trips WARN_ON() in xfrm_state_fini() and xfrm6_tunnel_net_exit() (panic with panic_on_warn), and the subsequent use-after-free \u2014 including spin_lock() on freed memory \u2014 reliably produces oopses, lock corruption, or a full kernel panic."
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: delete x-\u003etunnel 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\u0027t 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\u0027re going to lock x-\u003etunnel while x is locked."
          },
          {
            "lang": "es",
            "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nxfrm: eliminar x-\u003etunnel a medida que eliminamos x\n\nLos t\u00faneles de respaldo ipcomp actualmente se eliminan (de las diversas listas y tablas hash) a medida que el \u00faltimo estado de usuario que necesitaba ese respaldo es destruido (no eliminado). Si una referencia a ese estado de usuario a\u00fan existe, el estado de respaldo permanecer\u00e1 en las tablas hash/listas, lo que activar\u00e1 la ADVERTENCIA en xfrm_state_fini. Debido a esas referencias restantes, la correcci\u00f3n en el commit f75a2804da39 (\u201cxfrm: destruir xfrm_state sincr\u00f3nicamente en la ruta de salida de red\u201d) no est\u00e1 completa.\n\nRecientemente corregimos una situaci\u00f3n similar en TCP debido a la liberaci\u00f3n diferida de skbs (commit 9b6412e6979f (\u201ctcp: eliminar secpath al mismo tiempo que actualmente eliminamos dst\u201d)). Esto tambi\u00e9n puede ocurrir debido al reensamblaje de IP: los skbs con un secpath permanecen en la cola de reensamblaje hasta la destrucci\u00f3n de netns. Si no podemos garantizar que las colas se vac\u00eden para cuando se ejecute xfrm_state_fini, a\u00fan puede haber referencias a un xfrm_state (de usuario), impidiendo la eliminaci\u00f3n 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 \u00faltimo estado de usuario que depend\u00eda de \u00e9l haya sido eliminado. La destrucci\u00f3n seguir\u00e1 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-\u003etunnel mientras x est\u00e1 bloqueado."
          }
        ],
        "id": "CVE-2025-40215",
        "lastModified": "2026-10-19T21:10:00.160",
        "metrics": {
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                "attackComplexity": "LOW",
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                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
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                "scope": "UNCHANGED",
                "userInteraction": "NONE",
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                    "exploitation": "none"
                  },
                  {
                    "automatable": "no"
                  },
                  {
                    "technicalImpact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-06-16T19:56:10.578142Z",
                "version": "2.0.3"
              }
            }
          ]
        },
        "published": "2025-12-04T13:15:48.473",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "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",
            "url": "https://git.kernel.org/stable/c/dc3636912d41770466543623cb76e7b88fdb42c7"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Deferred"
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-07-30T08:48:19+00:00",
      "cve": "CVE-2025-40215",
      "id": "CVE-2025-40215",
      "initial_release_date": "2025-12-04T00:00:00+00:00",
      "product_status:known_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: xfrm: delete x-\u003etunnel as we delete x",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-40215.json",
      "version": "3"
    },
    "vulnrichment": {
      "containers": {
        "adp": [
          {
            "metrics": [
              {
                "other": {
                  "content": {
                    "id": "CVE-2025-40215",
                    "options": [
                      {
                        "Exploitation": "none"
                      },
                      {
                        "Automatable": "no"
                      },
                      {
                        "Technical Impact": "partial"
                      }
                    ],
                    "role": "CISA Coordinator",
                    "timestamp": "2026-06-16T19:56:10.578142Z",
                    "version": "2.0.3"
                  },
                  "type": "ssvc"
                }
              }
            ],
            "providerMetadata": {
              "dateUpdated": "2026-06-16T19:56:15.418Z",
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP"
            },
            "title": "CISA ADP Vulnrichment"
          }
        ],
        "cna": {
          "affected": [
            {
              "defaultStatus": "unaffected",
              "product": "Linux",
              "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",
              "vendor": "Linux",
              "versions": [
                {
                  "lessThan": "1b28a7fae0128fa140a7dccd995182ff6cd1c67b",
                  "status": "affected",
                  "version": "9d4139c76905833afcb77fe8ccc17f302a0eb9ab",
                  "versionType": "git"
                },
                {
                  "lessThan": "4b2c17d0f9be8b58bb30468bc81a4b61c985b04e",
                  "status": "affected",
                  "version": "9d4139c76905833afcb77fe8ccc17f302a0eb9ab",
                  "versionType": "git"
                },
                {
                  "lessThan": "0da961fa46da1b37ef868d9b603bd202136f8f8e",
                  "status": "affected",
                  "version": "9d4139c76905833afcb77fe8ccc17f302a0eb9ab",
                  "versionType": "git"
                },
                {
                  "lessThan": "d0e0d1097118461463b76562c7ebaabaa5b90b13",
                  "status": "affected",
                  "version": "9d4139c76905833afcb77fe8ccc17f302a0eb9ab",
                  "versionType": "git"
                },
                {
                  "lessThan": "dc3636912d41770466543623cb76e7b88fdb42c7",
                  "status": "affected",
                  "version": "9d4139c76905833afcb77fe8ccc17f302a0eb9ab",
                  "versionType": "git"
                },
                {
                  "lessThan": "b441cf3f8c4b8576639d20c8eb4aa32917602ecd",
                  "status": "affected",
                  "version": "9d4139c76905833afcb77fe8ccc17f302a0eb9ab",
                  "versionType": "git"
                }
              ]
            },
            {
              "defaultStatus": "affected",
              "product": "Linux",
              "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",
              "vendor": "Linux",
              "versions": [
                {
                  "status": "affected",
                  "version": "2.6.29"
                },
                {
                  "lessThan": "2.6.29",
                  "status": "unaffected",
                  "version": "0",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "5.10.*",
                  "status": "unaffected",
                  "version": "5.10.248",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "5.15.*",
                  "status": "unaffected",
                  "version": "5.15.198",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "6.1.*",
                  "status": "unaffected",
                  "version": "6.1.160",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "6.6.*",
                  "status": "unaffected",
                  "version": "6.6.120",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "6.12.*",
                  "status": "unaffected",
                  "version": "6.12.62",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "*",
                  "status": "unaffected",
                  "version": "6.16",
                  "versionType": "original_commit_for_fix"
                }
              ]
            }
          ],
          "cpeApplicability": [
            {
              "nodes": [
                {
                  "cpeMatch": [
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "5.10.248",
                      "versionStartIncluding": "2.6.29",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "5.15.198",
                      "versionStartIncluding": "2.6.29",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "6.6.120",
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                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "6.12.62",
                      "versionStartIncluding": "2.6.29",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "6.16",
                      "versionStartIncluding": "2.6.29",
                      "vulnerable": true
                    }
                  ],
                  "negate": false,
                  "operator": "OR"
                }
              ]
            }
          ],
          "descriptions": [
            {
              "lang": "en",
              "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: delete x-\u003etunnel 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\u0027t 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\u0027re going to lock x-\u003etunnel while x is locked."
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-05-11T21:44:59.604Z",
            "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "shortName": "Linux"
          },
          "references": [
            {
              "url": "https://git.kernel.org/stable/c/1b28a7fae0128fa140a7dccd995182ff6cd1c67b"
            },
            {
              "url": "https://git.kernel.org/stable/c/4b2c17d0f9be8b58bb30468bc81a4b61c985b04e"
            },
            {
              "url": "https://git.kernel.org/stable/c/0da961fa46da1b37ef868d9b603bd202136f8f8e"
            },
            {
              "url": "https://git.kernel.org/stable/c/d0e0d1097118461463b76562c7ebaabaa5b90b13"
            },
            {
              "url": "https://git.kernel.org/stable/c/dc3636912d41770466543623cb76e7b88fdb42c7"
            },
            {
              "url": "https://git.kernel.org/stable/c/b441cf3f8c4b8576639d20c8eb4aa32917602ecd"
            }
          ],
          "title": "xfrm: delete x-\u003etunnel as we delete x",
          "x_generator": {
            "engine": "bippy-1.2.0"
          }
        }
      },
      "cveMetadata": {
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "assignerShortName": "Linux",
        "cveId": "CVE-2025-40215",
        "datePublished": "2025-12-04T12:38:32.517Z",
        "dateReserved": "2025-04-16T07:20:57.179Z",
        "dateUpdated": "2026-06-16T19:56:19.286Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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