{
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              "content": {
                "id": "CVE-2026-55953",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
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                "role": "CISA Coordinator",
                "timestamp": "2026-07-27T18:33:59.966358Z",
                "version": "2.0.3"
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              "type": "ssvc"
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        "providerMetadata": {
          "dateUpdated": "2026-07-27T18:34:10.360Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
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            "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"
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            "ssl"
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          "packageName": "otp",
          "packageURL": "pkg:software-id/erlang.org/otp",
          "product": "OTP",
          "programFiles": [
            "lib/ssl/src/tls_handshake.erl",
            "lib/ssl/src/ssl_handshake.erl",
            "lib/ssl/src/ssl.erl"
          ],
          "programRoutines": [
            {
              "name": "tls_handshake:hello/5"
            },
            {
              "name": "ssl_handshake:handle_server_hello_extensions/9"
            },
            {
              "name": "ssl:connect/2"
            },
            {
              "name": "ssl:connect/3"
            },
            {
              "name": "ssl:connect/4"
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          ],
          "vendor": "Erlang",
          "versions": [
            {
              "lessThan": "17.0",
              "status": "unknown",
              "version": "0",
              "versionType": "otp"
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            {
              "lessThan": "27.3.4.15",
              "status": "affected",
              "version": "17.0",
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              "status": "affected",
              "version": "28.0",
              "versionType": "otp"
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            {
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              "status": "affected",
              "version": "29.0",
              "versionType": "otp"
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          ],
          "defaultStatus": "unaffected",
          "modules": [
            "tls_handshake",
            "ssl_handshake",
            "ssl"
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          "packageName": "ssl",
          "packageURL": "pkg:otp/ssl?repository_url=https:%2F%2Fgithub.com%2Ferlang%2Fotp\u0026vcs_url=git%2Bhttps:%2F%2Fgithub.com%2Ferlang%2Fotp.git",
          "product": "OTP",
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            "src/ssl_handshake.erl",
            "src/ssl.erl"
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              "name": "ssl:connect/2"
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              "name": "ssl:connect/3"
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              "name": "ssl:connect/4"
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          "repo": "https://github.com/erlang/otp",
          "vendor": "Erlang",
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              "lessThan": "5.3.4",
              "status": "unknown",
              "version": "0",
              "versionType": "otp"
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              "lessThan": "11.2.12.11",
              "status": "affected",
              "version": "5.3.4",
              "versionType": "otp"
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              "lessThan": "11.6.0.4",
              "status": "affected",
              "version": "11.3",
              "versionType": "otp"
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            {
              "lessThan": "11.7.4",
              "status": "affected",
              "version": "11.7",
              "versionType": "otp"
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        },
        {
          "collectionURL": "https://github.com",
          "cpes": [
            "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"
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          "defaultStatus": "unaffected",
          "modules": [
            "tls_handshake",
            "ssl_handshake",
            "ssl"
          ],
          "packageName": "erlang/otp",
          "packageURL": "pkg:github/erlang/otp",
          "product": "OTP",
          "programFiles": [
            "lib/ssl/src/tls_handshake.erl",
            "lib/ssl/src/ssl_handshake.erl",
            "lib/ssl/src/ssl.erl"
          ],
          "programRoutines": [
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              "name": "tls_handshake:hello/5"
            },
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              "name": "ssl_handshake:handle_server_hello_extensions/9"
            },
            {
              "name": "ssl:connect/2"
            },
            {
              "name": "ssl:connect/3"
            },
            {
              "name": "ssl:connect/4"
            }
          ],
          "repo": "https://github.com/erlang/otp",
          "vendor": "Erlang",
          "versions": [
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              "changes": [
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                  "at": "064e236414614f9085cbbbd6eacf0e43c02d1b4b",
                  "status": "unaffected"
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                  "status": "unaffected"
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              "status": "affected",
              "version": "84adefa331c4159d432d22840663c38f155cd4c1",
              "versionType": "git"
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      "configurations": [
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          "lang": "en",
          "supportingMedia": [
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              "type": "text/html",
              "value": "\u003cp\u003eThe vulnerability only affects TLS clients using TLS 1.2 (or earlier) or DTLS. TLS 1.3 client connections perform the cipher suite membership check and are not affected. Servers are not affected. Exploitation additionally requires an on-path (adversary-in-the-middle) attacker between the client and the intended server.\u003c/p\u003e"
            },
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              "type": "text/markdown",
              "value": "The vulnerability only affects TLS clients using TLS 1.2 (or earlier) or DTLS. TLS 1.3 client connections perform the cipher suite membership check and are not affected. Servers are not affected. Exploitation additionally requires an on-path (adversary-in-the-middle) attacker between the client and the intended server."
            }
          ],
          "value": "The vulnerability only affects TLS clients using TLS 1.2 (or earlier) or DTLS. TLS 1.3 client connections perform the cipher suite membership check and are not affected. Servers are not affected. Exploitation additionally requires an on-path (adversary-in-the-middle) attacker between the client and the intended server."
        }
      ],
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          "nodes": [
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              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "27.3.4.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "28.5.0.4",
                  "versionStartIncluding": "28.0",
                  "vulnerable": true
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                  "criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*",
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      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Jonatan M\u00e4nnchen / EEF"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "Ingela Anderton Andin"
        },
        {
          "lang": "en",
          "type": "remediation reviewer",
          "value": "Jakub Witczak"
        }
      ],
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              "value": "\u003cp\u003eThe Erlang/OTP \u003ccode\u003essl\u003c/code\u003e TLS 1.2 (and earlier) and DTLS client does not verify that the cipher suite selected by the server in \u003ccode\u003eServerHello\u003c/code\u003e was among the suites offered by the client in \u003ccode\u003eClientHello\u003c/code\u003e. The client-side \u003ccode\u003etls_handshake:hello/5\u003c/code\u003e handler validates the negotiated protocol version and the downgrade sentinel but hands the server-chosen suite directly to \u003ccode\u003essl_handshake:handle_server_hello_extensions/9\u003c/code\u003e, which installs it without a membership check. The TLS 1.3 client path performs this check (per RFC 8446), so it is not affected.\u003c/p\u003e\n\u003cp\u003eAn on-path attacker between the client and the intended server can respond with a \u003ccode\u003eServerHello\u003c/code\u003e selecting an anonymous key exchange suite such as \u003ccode\u003eTLS_DH_anon_*\u003c/code\u003e or \u003ccode\u003eTLS_ECDH_anon_*\u003c/code\u003e that the client never offered. Anonymous suites do not require the server to present a certificate, so the entire \u003ccode\u003everify_peer\u003c/code\u003e and \u003ccode\u003ecacerts\u003c/code\u003e configuration is bypassed: the attacker completes the handshake with its own ephemeral parameters, no certificate is validated, no hostname is checked, and \u003ccode\u003essl:connect\u003c/code\u003e returns \u003ccode\u003e{ok, Socket}\u003c/code\u003e. All subsequent application traffic is readable and modifiable by the attacker.\u003c/p\u003e\n\u003cp\u003eThis issue affects OTP from OTP\u0026nbsp;17.0 before OTP\u0026nbsp;27.3.4.15, from OTP\u0026nbsp;28.0 before OTP\u0026nbsp;28.5.0.4, and from OTP\u0026nbsp;29.0 before OTP\u0026nbsp;29.0.4, corresponding to ssl from 5.3.4 before 11.2.12.11, from 11.3 before 11.6.0.4, and from 11.7 before 11.7.4. Whether OTP before OTP\u0026nbsp;17.0, corresponding to ssl before 5.3.4, is affected is unknown.\u003c/p\u003e"
            },
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              "base64": false,
              "type": "text/markdown",
              "value": "The Erlang/OTP `ssl` TLS 1.2 (and earlier) and DTLS client does not verify that the cipher suite selected by the server in `ServerHello` was among the suites offered by the client in `ClientHello`. The client-side `tls_handshake:hello/5` handler validates the negotiated protocol version and the downgrade sentinel but hands the server-chosen suite directly to `ssl_handshake:handle_server_hello_extensions/9`, which installs it without a membership check. The TLS 1.3 client path performs this check (per RFC 8446), so it is not affected.\n\nAn on-path attacker between the client and the intended server can respond with a `ServerHello` selecting an anonymous key exchange suite such as `TLS_DH_anon_*` or `TLS_ECDH_anon_*` that the client never offered. Anonymous suites do not require the server to present a certificate, so the entire `verify_peer` and `cacerts` configuration is bypassed: the attacker completes the handshake with its own ephemeral parameters, no certificate is validated, no hostname is checked, and `ssl:connect` returns `{ok, Socket}`. All subsequent application traffic is readable and modifiable by the attacker.\n\nThis issue affects OTP from OTP\u00a017.0 before OTP\u00a027.3.4.15, from OTP\u00a028.0 before OTP\u00a028.5.0.4, and from OTP\u00a029.0 before OTP\u00a029.0.4, corresponding to ssl from 5.3.4 before 11.2.12.11, from 11.3 before 11.6.0.4, and from 11.7 before 11.7.4. Whether OTP before OTP\u00a017.0, corresponding to ssl before 5.3.4, is affected is unknown."
            }
          ],
          "value": "The Erlang/OTP ssl TLS 1.2 (and earlier) and DTLS client does not verify that the cipher suite selected by the server in ServerHello was among the suites offered by the client in ClientHello. The client-side tls_handshake:hello/5 handler validates the negotiated protocol version and the downgrade sentinel but hands the server-chosen suite directly to ssl_handshake:handle_server_hello_extensions/9, which installs it without a membership check. The TLS 1.3 client path performs this check (per RFC 8446), so it is not affected.\n\nAn on-path attacker between the client and the intended server can respond with a ServerHello selecting an anonymous key exchange suite such as TLS_DH_anon_* or TLS_ECDH_anon_* that the client never offered. Anonymous suites do not require the server to present a certificate, so the entire verify_peer and cacerts configuration is bypassed: the attacker completes the handshake with its own ephemeral parameters, no certificate is validated, no hostname is checked, and ssl:connect returns {ok, Socket}. All subsequent application traffic is readable and modifiable by the attacker.\n\nThis issue affects OTP from OTP\u00a017.0 before OTP\u00a027.3.4.15, from OTP\u00a028.0 before OTP\u00a028.5.0.4, and from OTP\u00a029.0 before OTP\u00a029.0.4, corresponding to ssl from 5.3.4 before 11.2.12.11, from 11.3 before 11.6.0.4, and from 11.7 before 11.7.4. Whether OTP before OTP\u00a017.0, corresponding to ssl before 5.3.4, is affected is unknown."
        }
      ],
      "impacts": [
        {
          "capecId": "CAPEC-94",
          "descriptions": [
            {
              "lang": "en",
              "value": "CAPEC-94 Adversary in the Middle (AiTM)"
            }
          ]
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 9.1,
            "baseSeverity": "CRITICAL",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "HIGH",
            "vulnIntegrityImpact": "HIGH",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
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          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-757",
              "description": "CWE-757 Selection of Less-Secure Algorithm During Negotiation (\u0027Algorithm Downgrade\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-08T01:06:57.579Z",
        "orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "shortName": "EEF"
      },
      "references": [
        {
          "tags": [
            "vendor-advisory",
            "related"
          ],
          "url": "https://github.com/erlang/otp/security/advisories/GHSA-c6cw-pr89-w882"
        },
        {
          "tags": [
            "related"
          ],
          "url": "https://cna.erlef.org/cves/CVE-2026-55953.html"
        },
        {
          "tags": [
            "related"
          ],
          "url": "https://osv.dev/vulnerability/EEF-CVE-2026-55953"
        },
        {
          "tags": [
            "x_version-scheme"
          ],
          "url": "https://www.erlang.org/doc/system/versions.html#order-of-versions"
        },
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/erlang/otp/commit/064e236414614f9085cbbbd6eacf0e43c02d1b4b"
        },
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/erlang/otp/commit/0a82596d425abe43dc2e0b3d74aa1557ef74051c"
        },
        {
          "tags": [
            "patch"
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          "url": "https://github.com/erlang/otp/commit/e6ff938116b2872bccc478af7fefb56627285b77"
        }
      ],
      "source": {
        "discovery": "INTERNAL"
      },
      "title": "TLS 1.2 and DTLS client accepts unoffered anonymous cipher suite, bypassing server authentication",
      "workarounds": [
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          "lang": "en",
          "supportingMedia": [
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              "value": "\u003cul\u003e\n\u003cli\u003eRestrict client connections to TLS 1.3 only by setting \u003ccode\u003eversions\u003c/code\u003e to \u003ccode\u003e[\u0027tlsv1.3\u0027]\u003c/code\u003e in the client\u0027s \u003ccode\u003essl\u003c/code\u003e options. The TLS 1.3 client path performs the required cipher suite membership check and is not affected.\u003c/li\u003e\n\u003c/ul\u003e"
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            {
              "base64": false,
              "type": "text/markdown",
              "value": "- Restrict client connections to TLS 1.3 only by setting `versions` to `[\u0027tlsv1.3\u0027]` in the client\u0027s `ssl` options. The TLS 1.3 client path performs the required cipher suite membership check and is not affected."
            }
          ],
          "value": "* Restrict client connections to TLS 1.3 only by setting versions to [\u0027tlsv1.3\u0027] in the client\u0027s ssl options. The TLS 1.3 client path performs the required cipher suite membership check and is not affected."
        }
      ]
    }
  },
  "cveMetadata": {
    "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
    "assignerShortName": "EEF",
    "cveId": "CVE-2026-55953",
    "datePublished": "2026-07-27T15:21:29.327Z",
    "dateReserved": "2026-06-17T17:55:15.686Z",
    "dateUpdated": "2026-09-08T01:06:57.579Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}