CVE-2025-40018 (GCVE-0-2025-40018)

Vulnerability from cvelistv5 – Published: 2025-10-24 11:44 – Updated: 2026-10-15 22:02
VLAI
Title
ipvs: Defer ip_vs_ftp unregister during netns cleanup
Summary
In the Linux kernel, the following vulnerability has been resolved: ipvs: Defer ip_vs_ftp unregister during netns cleanup On the netns cleanup path, __ip_vs_ftp_exit() may unregister ip_vs_ftp before connections with valid cp->app pointers are flushed, leading to a use-after-free. Fix this by introducing a global `exiting_module` flag, set to true in ip_vs_ftp_exit() before unregistering the pernet subsystem. In __ip_vs_ftp_exit(), skip ip_vs_ftp unregister if called during netns cleanup (when exiting_module is false) and defer it to __ip_vs_cleanup_batch(), which unregisters all apps after all connections are flushed. If called during module exit, unregister ip_vs_ftp immediately.
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: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-15 21:56 UTC
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6641 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 61b1ab4583e275af216c8454b9256de680499b19 , < 8a6ecab3847c213ce2855b0378e63ce839085de3 (git)
Affected: 61b1ab4583e275af216c8454b9256de680499b19 , < 421b1ae1574dfdda68b835c15ac4921ec0030182 (git)
Affected: 61b1ab4583e275af216c8454b9256de680499b19 , < 1d79471414d7b9424d699afff2aa79fff322f52d (git)
Affected: 61b1ab4583e275af216c8454b9256de680499b19 , < 53717f8a4347b78eac6488072ad8e5adbaff38d9 (git)
Affected: 61b1ab4583e275af216c8454b9256de680499b19 , < 8cbe2a21d85727b66d7c591fd5d83df0d8c4f757 (git)
Affected: 61b1ab4583e275af216c8454b9256de680499b19 , < dc1a481359a72ee7e548f1f5da671282a7c13b8f (git)
Affected: 61b1ab4583e275af216c8454b9256de680499b19 , < a343811ef138a265407167294275201621e9ebb2 (git)
Affected: 61b1ab4583e275af216c8454b9256de680499b19 , < 134121bfd99a06d44ef5ba15a9beb075297c0821 (git)
guessed Create a notification for this product.
Linux Linux Affected: 2.6.39
Unaffected: 0 , < 2.6.39 (semver)
Unaffected: 5.4.301 , ≤ 5.4.* (semver)
Unaffected: 5.10.246 , ≤ 5.10.* (semver)
Unaffected: 5.15.195 , ≤ 5.15.* (semver)
Unaffected: 6.1.156 , ≤ 6.1.* (semver)
Unaffected: 6.6.112 , ≤ 6.6.* (semver)
Unaffected: 6.12.53 , ≤ 6.12.* (semver)
Unaffected: 6.17.3 , ≤ 6.17.* (semver)
Unaffected: 6.18 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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              "value": "AV:L - The use-after-free is triggered by network namespace teardown, which requires local access (unshare/exit of a netns, or `ip netns del`); while a remote client can populate the FTP-bound IPVS connections through the load balancer, the free-and-use sequence itself is driven locally.\nAC:L - The bad ordering is deterministic \u2014 pernet exit callbacks always run in reverse registration order, so `__ip_vs_ftp_exit()` always precedes the connection flush \u2014 and the attacker controls both the connection creation and the netns destruction, with ordinary heap grooming sufficing to reclaim the freed `ip_vs_app` objects.\nPR:L - Configuring the IPVS FTP virtual service needs CAP_NET_ADMIN, but `do_ip_vs_set_ctl()` checks `ns_capable(net-\u003euser_ns, CAP_NET_ADMIN)` and IPVS was explicitly made usable in non-init user namespaces, so an unprivileged local user obtains it with `unshare -Urn`.\nUI:N - The attacker performs the entire sequence \u2014 namespace creation, IPVS service setup, connection establishment and namespace teardown \u2014 with no action from any other user.\nS:U - The corruption and any resulting privilege escalation stay within the kernel\u0027s own security authority; no VM, IOMMU, or other trust boundary is crossed.\nC:H - `ip_vs_unbind_app()` dereferences the freed `inc` and the already-kfree()\u0027d `inc-\u003eapp`, so reclaiming those slab objects lets an attacker read and leak kernel heap contents and pointers.\nI:H - The use-after-free yields a write primitive (`atomic_dec(\u0026inc-\u003eusecnt)` and `module_put()` through a dangling `inc-\u003eapp` pointer) plus an indirect call through the freed `inc-\u003edone_conn`/`unbind_conn` function pointers, which is a control-flow hijack primitive after heap spraying.\nA:H - Even unexploited, the use-after-free calls a function pointer from reclaimed memory and corrupts refcounts during netns cleanup, reliably producing a kernel oops or panic."
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            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipvs: Defer ip_vs_ftp unregister during netns cleanup\n\nOn the netns cleanup path, __ip_vs_ftp_exit() may unregister ip_vs_ftp\nbefore connections with valid cp-\u003eapp pointers are flushed, leading to a\nuse-after-free.\n\nFix this by introducing a global `exiting_module` flag, set to true in\nip_vs_ftp_exit() before unregistering the pernet subsystem. In\n__ip_vs_ftp_exit(), skip ip_vs_ftp unregister if called during netns\ncleanup (when exiting_module is false) and defer it to\n__ip_vs_cleanup_batch(), which unregisters all apps after all connections\nare flushed. If called during module exit, unregister ip_vs_ftp\nimmediately."
          },
          {
            "lang": "es",
            "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nipvs: Aplazar la anulaci\u00f3n de registro de ip_vs_ftp durante la limpieza de netns\n\nEn la ruta de limpieza de netns, __ip_vs_ftp_exit() puede anular el registro de ip_vs_ftp antes de que se vac\u00eden las conexiones con punteros cp-\u003eapp v\u00e1lidos, lo que lleva a un uso despu\u00e9s de liberaci\u00f3n.\n\nEsto se soluciona introduciendo una bandera global \u0027exiting_module\u0027, establecida en verdadero en ip_vs_ftp_exit() antes de anular el registro del subsistema pernet. En __ip_vs_ftp_exit(), omitir la anulaci\u00f3n de registro de ip_vs_ftp si se llama durante la limpieza de netns (cuando \u0027exiting_module\u0027 es falso) y aplazarla a __ip_vs_cleanup_batch(), que anula el registro de todas las aplicaciones despu\u00e9s de que se vac\u00edan todas las conexiones. Si se llama durante la salida del m\u00f3dulo, anular el registro de ip_vs_ftp inmediatamente."
          }
        ],
        "id": "CVE-2025-40018",
        "lastModified": "2026-10-19T21:10:00.160",
        "metrics": {
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                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
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                "version": "2.0.3"
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          },
          {
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            "url": "https://git.kernel.org/stable/c/a343811ef138a265407167294275201621e9ebb2"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/dc1a481359a72ee7e548f1f5da671282a7c13b8f"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Deferred"
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-11-09T17:44:52+00:00",
      "cve": "CVE-2025-40018",
      "id": "CVE-2025-40018",
      "initial_release_date": "2025-10-24T00:00:00+00:00",
      "product_status:known_affected": "200",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: ipvs: Defer ip_vs_ftp unregister during netns cleanup",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-40018.json",
      "version": "3"
    },
    "vulnrichment": {
      "containers": {
        "adp": [
          {
            "metrics": [
              {
                "other": {
                  "content": {
                    "id": "CVE-2025-40018",
                    "options": [
                      {
                        "Exploitation": "none"
                      },
                      {
                        "Automatable": "no"
                      },
                      {
                        "Technical Impact": "total"
                      }
                    ],
                    "role": "CISA Coordinator",
                    "timestamp": "2026-10-15T21:56:10.486457Z",
                    "version": "2.0.3"
                  },
                  "type": "ssvc"
                }
              }
            ],
            "providerMetadata": {
              "dateUpdated": "2026-10-15T21:56:11.399Z",
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP"
            },
            "title": "CISA ADP Vulnrichment"
          }
        ],
        "cna": {
          "affected": [
            {
              "defaultStatus": "unaffected",
              "product": "Linux",
              "programFiles": [
                "net/netfilter/ipvs/ip_vs_ftp.c"
              ],
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "vendor": "Linux",
              "versions": [
                {
                  "lessThan": "8a6ecab3847c213ce2855b0378e63ce839085de3",
                  "status": "affected",
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                  "versionType": "git"
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                {
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                  "status": "affected",
                  "version": "61b1ab4583e275af216c8454b9256de680499b19",
                  "versionType": "git"
                },
                {
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              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "vendor": "Linux",
              "versions": [
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                  "version": "2.6.39"
                },
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                  "status": "unaffected",
                  "version": "0",
                  "versionType": "semver"
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                  "version": "5.4.301",
                  "versionType": "semver"
                },
                {
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                  "status": "unaffected",
                  "version": "5.10.246",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "5.15.*",
                  "status": "unaffected",
                  "version": "5.15.195",
                  "versionType": "semver"
                },
                {
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                  "status": "unaffected",
                  "version": "6.1.156",
                  "versionType": "semver"
                },
                {
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                  "status": "unaffected",
                  "version": "6.6.112",
                  "versionType": "semver"
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                {
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                  "status": "unaffected",
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                {
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                  "status": "unaffected",
                  "version": "6.17.3",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "*",
                  "status": "unaffected",
                  "version": "6.18",
                  "versionType": "original_commit_for_fix"
                }
              ]
            }
          ],
          "cpeApplicability": [
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                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "5.10.246",
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                    }
                  ],
                  "negate": false,
                  "operator": "OR"
                }
              ]
            }
          ],
          "descriptions": [
            {
              "lang": "en",
              "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipvs: Defer ip_vs_ftp unregister during netns cleanup\n\nOn the netns cleanup path, __ip_vs_ftp_exit() may unregister ip_vs_ftp\nbefore connections with valid cp-\u003eapp pointers are flushed, leading to a\nuse-after-free.\n\nFix this by introducing a global `exiting_module` flag, set to true in\nip_vs_ftp_exit() before unregistering the pernet subsystem. In\n__ip_vs_ftp_exit(), skip ip_vs_ftp unregister if called during netns\ncleanup (when exiting_module is false) and defer it to\n__ip_vs_cleanup_batch(), which unregisters all apps after all connections\nare flushed. If called during module exit, unregister ip_vs_ftp\nimmediately."
            }
          ],
          "metrics": [
            {
              "cvssV3_1": {
                "baseScore": 7.8,
                "baseSeverity": "HIGH",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
                "version": "3.1"
              },
              "scenarios": [
                {
                  "lang": "en",
                  "value": "AV:L - The use-after-free is triggered by network namespace teardown, which requires local access (unshare/exit of a netns, or `ip netns del`); while a remote client can populate the FTP-bound IPVS connections through the load balancer, the free-and-use sequence itself is driven locally.\nAC:L - The bad ordering is deterministic \u2014 pernet exit callbacks always run in reverse registration order, so `__ip_vs_ftp_exit()` always precedes the connection flush \u2014 and the attacker controls both the connection creation and the netns destruction, with ordinary heap grooming sufficing to reclaim the freed `ip_vs_app` objects.\nPR:L - Configuring the IPVS FTP virtual service needs CAP_NET_ADMIN, but `do_ip_vs_set_ctl()` checks `ns_capable(net-\u003euser_ns, CAP_NET_ADMIN)` and IPVS was explicitly made usable in non-init user namespaces, so an unprivileged local user obtains it with `unshare -Urn`.\nUI:N - The attacker performs the entire sequence \u2014 namespace creation, IPVS service setup, connection establishment and namespace teardown \u2014 with no action from any other user.\nS:U - The corruption and any resulting privilege escalation stay within the kernel\u0027s own security authority; no VM, IOMMU, or other trust boundary is crossed.\nC:H - `ip_vs_unbind_app()` dereferences the freed `inc` and the already-kfree()\u0027d `inc-\u003eapp`, so reclaiming those slab objects lets an attacker read and leak kernel heap contents and pointers.\nI:H - The use-after-free yields a write primitive (`atomic_dec(\u0026inc-\u003eusecnt)` and `module_put()` through a dangling `inc-\u003eapp` pointer) plus an indirect call through the freed `inc-\u003edone_conn`/`unbind_conn` function pointers, which is a control-flow hijack primitive after heap spraying.\nA:H - Even unexploited, the use-after-free calls a function pointer from reclaimed memory and corrupts refcounts during netns cleanup, reliably producing a kernel oops or panic."
                }
              ]
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-08-05T12:07:05.588Z",
            "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "shortName": "Linux"
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            },
            {
              "url": "https://git.kernel.org/stable/c/134121bfd99a06d44ef5ba15a9beb075297c0821"
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            "engine": "bippy-1.2.0"
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      "cveMetadata": {
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        "assignerShortName": "Linux",
        "cveId": "CVE-2025-40018",
        "datePublished": "2025-10-24T11:44:28.955Z",
        "dateReserved": "2025-04-16T07:20:57.152Z",
        "dateUpdated": "2026-10-15T22:02:36.226Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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