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
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)
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)
Create a notification for this product.
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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."
        }
      ],
      "metrics": [
        {
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            "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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      "references": [
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          "url": "https://git.kernel.org/stable/c/8a6ecab3847c213ce2855b0378e63ce839085de3"
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      "title": "ipvs: Defer ip_vs_ftp unregister during netns cleanup",
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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": "2026-08-05T12:07:05.588Z",
    "state": "PUBLISHED"
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  "dataVersion": "5.2",
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      "cve": "CVE-2025-40018",
      "date": "2026-08-12",
      "epss": "0.0014",
      "percentile": "0.03831"
    },
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      "cve": "CVE-2025-40018",
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      "product_status:fixed": "1",
      "product_status:known_affected": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "ipvs: Defer ip_vs_ftp unregister during netns cleanup",
      "url": "https://msrc.microsoft.com/csaf/vex/2025/msrc_cve-2025-40018.json",
      "version": "1"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-40018\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-10-24T12:15:37.703\",\"lastModified\":\"2026-07-30T06:24:06.253\",\"vulnStatus\":\"Deferred\",\"cveTags\":[],\"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.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"net/netfilter/ipvs/ip_vs_ftp.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"61b1ab4583e275af216c8454b9256de680499b19\",\"lessThan\":\"8a6ecab3847c213ce2855b0378e63ce839085de3\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"61b1ab4583e275af216c8454b9256de680499b19\",\"lessThan\":\"421b1ae1574dfdda68b835c15ac4921ec0030182\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"61b1ab4583e275af216c8454b9256de680499b19\",\"lessThan\":\"1d79471414d7b9424d699afff2aa79fff322f52d\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"61b1ab4583e275af216c8454b9256de680499b19\",\"lessThan\":\"53717f8a4347b78eac6488072ad8e5adbaff38d9\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"61b1ab4583e275af216c8454b9256de680499b19\",\"lessThan\":\"8cbe2a21d85727b66d7c591fd5d83df0d8c4f757\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"61b1ab4583e275af216c8454b9256de680499b19\",\"lessThan\":\"dc1a481359a72ee7e548f1f5da671282a7c13b8f\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"61b1ab4583e275af216c8454b9256de680499b19\",\"lessThan\":\"a343811ef138a265407167294275201621e9ebb2\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"61b1ab4583e275af216c8454b9256de680499b19\",\"lessThan\":\"134121bfd99a06d44ef5ba15a9beb075297c0821\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"net/netfilter/ipvs/ip_vs_ftp.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"2.6.39\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"2.6.39\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.4.301\",\"lessThanOrEqual\":\"5.4.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.10.246\",\"lessThanOrEqual\":\"5.10.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.15.195\",\"lessThanOrEqual\":\"5.15.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.1.156\",\"lessThanOrEqual\":\"6.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.112\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.53\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.17.3\",\"lessThanOrEqual\":\"6.17.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18\",\"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}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/134121bfd99a06d44ef5ba15a9beb075297c0821\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/1d79471414d7b9424d699afff2aa79fff322f52d\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/421b1ae1574dfdda68b835c15ac4921ec0030182\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/53717f8a4347b78eac6488072ad8e5adbaff38d9\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/8a6ecab3847c213ce2855b0378e63ce839085de3\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/8cbe2a21d85727b66d7c591fd5d83df0d8c4f757\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/a343811ef138a265407167294275201621e9ebb2\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/dc1a481359a72ee7e548f1f5da671282a7c13b8f\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "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"
    }
  }
}



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