FKIE_CVE-2026-27624

Vulnerability from fkie_nvd - Published: 2026-02-25 05:17 - Updated: 2026-02-27 18:04
Severity ?
7.2 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
6.5 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Summary
Coturn is a free open source implementation of TURN and STUN Server. Coturn is commonly configured to block loopback and internal ranges using "denied-peer-ip" and/or default loopback restrictions. CVE-2020-26262 addressed bypasses involving "0.0.0.0", "[::1]" and "[::]", but IPv4-mapped IPv6 is not covered. When sending a "CreatePermission" or "ChannelBind" request with the "XOR-PEER-ADDRESS" value of "::ffff:127.0.0.1", a successful response is received, even though "127.0.0.0/8" is blocked via "denied-peer-ip". The root cause is that, prior to the updated fix implemented in version 4.9.0, three functions in "src/client/ns_turn_ioaddr.c" do not check "IN6_IS_ADDR_V4MAPPED". "ioa_addr_is_loopback()" checks "127.x.x.x" (AF_INET) and "::1" (AF_INET6), but not "::ffff:127.0.0.1." "ioa_addr_is_zero()" checks "0.0.0.0" and "::", but not "::ffff:0.0.0.0." "addr_less_eq()" used by "ioa_addr_in_range()" for "denied-peer-ip" matching: when the range is AF_INET and the peer is AF_INET6, the comparison returns 0 without extracting the embedded IPv4. Version 4.9.0 contains an updated fix to address the bypass of the fix for CVE-2020-26262.
References
security-advisories@github.comhttps://github.com/coturn/coturn/commit/b80eb898ba26552600770162c26a8ae7f3661b0bPatch
security-advisories@github.comhttps://github.com/coturn/coturn/security/advisories/GHSA-6g6j-r9rf-cm7pNot Applicable
security-advisories@github.comhttps://github.com/coturn/coturn/security/advisories/GHSA-j8mm-mpf8-gvjgExploit, Vendor Advisory
134c704f-9b21-4f2e-91b3-4a467353bcc0https://github.com/coturn/coturn/security/advisories/GHSA-6g6j-r9rf-cm7pNot Applicable
134c704f-9b21-4f2e-91b3-4a467353bcc0https://github.com/coturn/coturn/security/advisories/GHSA-j8mm-mpf8-gvjgExploit, Vendor Advisory
Impacted products
Vendor Product Version
coturn_project coturn *
To clipboard 

{
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:coturn_project:coturn:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "5C4DE18B-B9AA-4314-B584-7BA316D5D7DB",
              "versionEndExcluding": "4.9.0",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Coturn is a free open source implementation of TURN and STUN Server. Coturn is commonly configured to block loopback and internal ranges using \"denied-peer-ip\" and/or default loopback restrictions. CVE-2020-26262 addressed bypasses involving \"0.0.0.0\", \"[::1]\" and \"[::]\", but IPv4-mapped IPv6 is not covered. When sending a \"CreatePermission\" or \"ChannelBind\" request with the \"XOR-PEER-ADDRESS\" value of \"::ffff:127.0.0.1\", a successful response is received, even though \"127.0.0.0/8\" is blocked via \"denied-peer-ip\". The root cause is that, prior to the updated fix implemented in version 4.9.0, three functions in \"src/client/ns_turn_ioaddr.c\" do not check \"IN6_IS_ADDR_V4MAPPED\". \"ioa_addr_is_loopback()\" checks \"127.x.x.x\" (AF_INET) and \"::1\" (AF_INET6), but not \"::ffff:127.0.0.1.\" \"ioa_addr_is_zero()\" checks \"0.0.0.0\" and \"::\", but not \"::ffff:0.0.0.0.\" \"addr_less_eq()\" used by \"ioa_addr_in_range()\" for \"denied-peer-ip\" matching: when the range is AF_INET and the peer is AF_INET6, the comparison returns 0 without extracting the embedded IPv4. Version 4.9.0 contains an updated fix to address the bypass of the fix for CVE-2020-26262."
    },
    {
      "lang": "es",
      "value": "Coturn es una implementaci\u00f3n de c\u00f3digo abierto gratuita de servidor TURN y STUN. Coturn se configura com\u00fanmente para bloquear rangos de loopback e internos usando \u0027denied-peer-ip\u0027 y/o restricciones de loopback predeterminadas. CVE-2020-26262 abord\u00f3 evasiones que involucran \u00270.0.0.0\u0027, \u0027[::1]\u0027 y \u0027[::]\u0027, pero IPv6 mapeado a IPv4 no est\u00e1 cubierto. Al enviar una solicitud \u0027CreatePermission\u0027 o \u0027ChannelBind\u0027 con el valor \u0027XOR-PEER-ADDRESS\u0027 de \u0027::ffff:127.0.0.1\u0027, se recibe una respuesta exitosa, aunque \u0027127.0.0.0/8\u0027 est\u00e1 bloqueado a trav\u00e9s de \u0027denied-peer-ip\u0027. La causa ra\u00edz es que, antes de la correcci\u00f3n actualizada implementada en la versi\u00f3n 4.9.0, tres funciones en \u0027src/client/ns_turn_ioaddr.c\u0027 no verifican \u0027IN6_IS_ADDR_V4MAPPED\u0027. \u0027ioa_addr_is_loopback()\u0027 verifica \u0027127.x.x.x\u0027 (AF_INET) y \u0027::1\u0027 (AF_INET6), pero no \u0027::ffff:127.0.0.1\u0027. \u0027ioa_addr_is_zero()\u0027 verifica \u00270.0.0.0\u0027 y \u0027::\u0027, pero no \u0027::ffff:0.0.0.0\u0027. \u0027addr_less_eq()\u0027 utilizada por \u0027ioa_addr_in_range()\u0027 para la coincidencia de \u0027denied-peer-ip\u0027: cuando el rango es AF_INET y el par es AF_INET6, la comparaci\u00f3n devuelve 0 sin extraer el IPv4 incrustado. La versi\u00f3n 4.9.0 contiene una correcci\u00f3n actualizada para abordar la evasi\u00f3n de la correcci\u00f3n para CVE-2020-26262."
    }
  ],
  "id": "CVE-2026-27624",
  "lastModified": "2026-02-27T18:04:29.457",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 7.2,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "LOW",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "CHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 2.7,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      },
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 6.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "LOW",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 2.5,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2026-02-25T05:17:25.380",
  "references": [
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Patch"
      ],
      "url": "https://github.com/coturn/coturn/commit/b80eb898ba26552600770162c26a8ae7f3661b0b"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Not Applicable"
      ],
      "url": "https://github.com/coturn/coturn/security/advisories/GHSA-6g6j-r9rf-cm7p"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Exploit",
        "Vendor Advisory"
      ],
      "url": "https://github.com/coturn/coturn/security/advisories/GHSA-j8mm-mpf8-gvjg"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "tags": [
        "Not Applicable"
      ],
      "url": "https://github.com/coturn/coturn/security/advisories/GHSA-6g6j-r9rf-cm7p"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "tags": [
        "Exploit",
        "Vendor Advisory"
      ],
      "url": "https://github.com/coturn/coturn/security/advisories/GHSA-j8mm-mpf8-gvjg"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-284"
        },
        {
          "lang": "en",
          "value": "CWE-441"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}


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