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

Vulnerability from cvelistv5 – Published: 2025-10-24 11:44 – Updated: 2026-08-05 12:07
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
Assigner
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)
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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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    "datePublished": "2025-10-24T11:44:28.955Z",
    "dateReserved": "2025-04-16T07:20:57.152Z",
    "dateUpdated": "2026-08-05T12:07:05.588Z",
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        "descriptions": [
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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."
          }
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        "id": "CVE-2025-40018",
        "lastModified": "2026-07-30T06:24:06.253",
        "metrics": {
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                "confidentialityImpact": "HIGH",
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                "scope": "UNCHANGED",
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              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
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        "published": "2025-10-24T12:15:37.703",
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        "vulnStatus": "Deferred"
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      "current_release_date": "2026-07-30T08:52:39+00:00",
      "cve": "CVE-2025-40018",
      "id": "CVE-2025-40018",
      "initial_release_date": "2025-10-24T00:00:00+00:00",
      "product_status:known_affected": "274",
      "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"
    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2026-09-12T23:51:22Z",
      "cve": "CVE-2025-40018",
      "id": "CVE-2025-40018",
      "initial_release_date": "2025-10-24T23:24:26Z",
      "product_status:first_fixed": "2",
      "product_status:known_affected": "466",
      "product_status:known_not_affected": "35",
      "product_status:recommended": "880",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2025-40018",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2025-40018.json",
      "version": "58"
    }
  }
}



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Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.


Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.