CVE-2025-22021 (GCVE-0-2025-22021)
Vulnerability from cvelistv5
Published
2025-04-16 10:20
Modified
2025-05-26 05:16
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: netfilter: socket: Lookup orig tuple for IPv6 SNAT nf_sk_lookup_slow_v4 does the conntrack lookup for IPv4 packets to restore the original 5-tuple in case of SNAT, to be able to find the right socket (if any). Then socket_match() can correctly check whether the socket was transparent. However, the IPv6 counterpart (nf_sk_lookup_slow_v6) lacks this conntrack lookup, making xt_socket fail to match on the socket when the packet was SNATed. Add the same logic to nf_sk_lookup_slow_v6. IPv6 SNAT is used in Kubernetes clusters for pod-to-world packets, as pods' addresses are in the fd00::/8 ULA subnet and need to be replaced with the node's external address. Cilium leverages Envoy to enforce L7 policies, and Envoy uses transparent sockets. Cilium inserts an iptables prerouting rule that matches on `-m socket --transparent` and redirects the packets to localhost, but it fails to match SNATed IPv6 packets due to that missing conntrack lookup.
References
Impacted products
Vendor Product Version
Linux Linux Version: eb31628e37a0a4e01fffd79dcc7f815d2357f53a
Version: eb31628e37a0a4e01fffd79dcc7f815d2357f53a
Version: eb31628e37a0a4e01fffd79dcc7f815d2357f53a
Version: eb31628e37a0a4e01fffd79dcc7f815d2357f53a
Version: eb31628e37a0a4e01fffd79dcc7f815d2357f53a
Version: eb31628e37a0a4e01fffd79dcc7f815d2357f53a
Version: eb31628e37a0a4e01fffd79dcc7f815d2357f53a
Version: eb31628e37a0a4e01fffd79dcc7f815d2357f53a
Version: eb31628e37a0a4e01fffd79dcc7f815d2357f53a
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ipv6/netfilter/nf_socket_ipv6.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "versionType": "git"
            },
            {
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            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/ipv6/netfilter/nf_socket_ipv6.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "3.13"
            },
            {
              "lessThan": "3.13",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.4.*",
              "status": "unaffected",
              "version": "5.4.292",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.236",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.180",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.133",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.86",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.22",
              "versionType": "semver"
            },
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              "lessThanOrEqual": "6.13.*",
              "status": "unaffected",
              "version": "6.13.10",
              "versionType": "semver"
            },
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              "lessThanOrEqual": "6.14.*",
              "status": "unaffected",
              "version": "6.14.1",
              "versionType": "semver"
            },
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              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.15",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
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                  "versionEndExcluding": "5.4.292",
                  "versionStartIncluding": "3.13",
                  "vulnerable": true
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                  "versionEndExcluding": "5.10.236",
                  "versionStartIncluding": "3.13",
                  "vulnerable": true
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              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: socket: Lookup orig tuple for IPv6 SNAT\n\nnf_sk_lookup_slow_v4 does the conntrack lookup for IPv4 packets to\nrestore the original 5-tuple in case of SNAT, to be able to find the\nright socket (if any). Then socket_match() can correctly check whether\nthe socket was transparent.\n\nHowever, the IPv6 counterpart (nf_sk_lookup_slow_v6) lacks this\nconntrack lookup, making xt_socket fail to match on the socket when the\npacket was SNATed. Add the same logic to nf_sk_lookup_slow_v6.\n\nIPv6 SNAT is used in Kubernetes clusters for pod-to-world packets, as\npods\u0027 addresses are in the fd00::/8 ULA subnet and need to be replaced\nwith the node\u0027s external address. Cilium leverages Envoy to enforce L7\npolicies, and Envoy uses transparent sockets. Cilium inserts an iptables\nprerouting rule that matches on `-m socket --transparent` and redirects\nthe packets to localhost, but it fails to match SNATed IPv6 packets due\nto that missing conntrack lookup."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-05-26T05:16:46.403Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/6488b96a79a26e19100ad872622f04e93b638d7f"
        },
        {
          "url": "https://git.kernel.org/stable/c/58ab63d3ded2ca6141357a2b24eee8453d0f871d"
        },
        {
          "url": "https://git.kernel.org/stable/c/1ca2169cc19dca893c7aae6af122852097435d16"
        },
        {
          "url": "https://git.kernel.org/stable/c/1ec43100f7123010730b7ddfc3d5c2eac19e70e7"
        },
        {
          "url": "https://git.kernel.org/stable/c/5251041573850e5020cd447374e23010be698898"
        },
        {
          "url": "https://git.kernel.org/stable/c/2bb139e483f8cbe488d19d8c1135ac3615e2668c"
        },
        {
          "url": "https://git.kernel.org/stable/c/41904cbb343d115931d6bf79aa2c815cac4ef72b"
        },
        {
          "url": "https://git.kernel.org/stable/c/221c27259324ec1404f028d4f5a0f2ae7f63ee23"
        },
        {
          "url": "https://git.kernel.org/stable/c/932b32ffd7604fb00b5c57e239a3cc4d901ccf6e"
        }
      ],
      "title": "netfilter: socket: Lookup orig tuple for IPv6 SNAT",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-22021",
    "datePublished": "2025-04-16T10:20:37.695Z",
    "dateReserved": "2024-12-29T08:45:45.807Z",
    "dateUpdated": "2025-05-26T05:16:46.403Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-22021\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-04-16T11:15:42.773\",\"lastModified\":\"2025-04-16T13:25:37.340\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nnetfilter: socket: Lookup orig tuple for IPv6 SNAT\\n\\nnf_sk_lookup_slow_v4 does the conntrack lookup for IPv4 packets to\\nrestore the original 5-tuple in case of SNAT, to be able to find the\\nright socket (if any). Then socket_match() can correctly check whether\\nthe socket was transparent.\\n\\nHowever, the IPv6 counterpart (nf_sk_lookup_slow_v6) lacks this\\nconntrack lookup, making xt_socket fail to match on the socket when the\\npacket was SNATed. Add the same logic to nf_sk_lookup_slow_v6.\\n\\nIPv6 SNAT is used in Kubernetes clusters for pod-to-world packets, as\\npods\u0027 addresses are in the fd00::/8 ULA subnet and need to be replaced\\nwith the node\u0027s external address. Cilium leverages Envoy to enforce L7\\npolicies, and Envoy uses transparent sockets. Cilium inserts an iptables\\nprerouting rule that matches on `-m socket --transparent` and redirects\\nthe packets to localhost, but it fails to match SNATed IPv6 packets due\\nto that missing conntrack lookup.\"},{\"lang\":\"es\",\"value\":\"En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: netfilter: socket: Lookup orig tuple for IPv6 SNAT nf_sk_lookup_slow_v4 realiza la b\u00fasqueda conntrack de paquetes IPv4 para restaurar la 5-tupla original en caso de SNAT, para poder encontrar el socket correcto (si lo hay). Entonces socket_match() puede verificar correctamente si el socket era transparente. Sin embargo, la contraparte IPv6 (nf_sk_lookup_slow_v6) carece de esta b\u00fasqueda conntrack, lo que hace que xt_socket no coincida en el socket cuando el paquete fue SNATed. Agregue la misma l\u00f3gica a nf_sk_lookup_slow_v6. SNAT IPv6 se usa en cl\u00fasteres de Kubernetes para paquetes pod-to-world, ya que las direcciones de los pods est\u00e1n en la subred fd00::/8 ULA y deben reemplazarse con la direcci\u00f3n externa del nodo. Cilium utiliza Envoy para implementar pol\u00edticas L7, y Envoy utiliza sockets transparentes. Cilium inserta una regla de preenrutamiento de iptables que coincide con `-m socket --transparent` y redirige los paquetes a localhost, pero no coincide con los paquetes IPv6 SNAT debido a la falta de b\u00fasqueda de conntrack.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/1ca2169cc19dca893c7aae6af122852097435d16\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/1ec43100f7123010730b7ddfc3d5c2eac19e70e7\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/221c27259324ec1404f028d4f5a0f2ae7f63ee23\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/2bb139e483f8cbe488d19d8c1135ac3615e2668c\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/41904cbb343d115931d6bf79aa2c815cac4ef72b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/5251041573850e5020cd447374e23010be698898\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/58ab63d3ded2ca6141357a2b24eee8453d0f871d\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/6488b96a79a26e19100ad872622f04e93b638d7f\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/932b32ffd7604fb00b5c57e239a3cc4d901ccf6e\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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