{
  "schemaVersion": 1,
  "attribution": [
    {
      "source": "CISA Known Exploited Vulnerabilities",
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog",
      "licence": "US government work"
    },
    {
      "source": "GitHub Advisory Database",
      "url": "https://github.com/advisories",
      "licence": "CC BY 4.0"
    },
    {
      "source": "Have I Been Pwned",
      "url": "https://haveibeenpwned.com/",
      "licence": "CC BY 4.0"
    },
    {
      "source": "CVE Program (CVE records)",
      "url": "https://www.cve.org/Legal/TermsOfUse",
      "licence": "CVE Terms of Use",
      "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.",
      "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy."
    },
    {
      "source": "FIRST EPSS",
      "url": "https://www.first.org/epss/",
      "licence": "free to use; FIRST requests attribution"
    }
  ],
  "record": {
    "id": "CVE-2026-42790",
    "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-42790",
    "idYear": 2026,
    "status": "PUBLISHED",
    "publishedAt": "2026-05-27T15:09:01.860Z",
    "updatedAt": "2026-09-18T12:04:51.323Z",
    "importedAt": "2026-10-24T01:58:08.712Z",
    "snapshot": {
      "id": "cve_2026-10-24_midnight_baseline",
      "at": "2026-10-24T00:00:00.000Z",
      "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z"
    },
    "facts": {
      "title": "nameConstraints DNS bypass via subject CommonName fallback in public_key hostname verification",
      "summary": "Improper Certificate Validation vulnerability in Erlang OTP public_key (pubkey_cert and public_key modules) allows a DNS nameConstraints bypass via subject CommonName fallback in TLS hostname verification.\n\nTwo flaws combine to allow a subordinate CA whose DNS nameConstraints are restricted (e.g. permitted;DNS:allowed.example.com) to issue a leaf certificate that an OTP TLS client accepts as a valid identity for an out-of-scope hostname (e.g. victim.example.com):\n\nFirst, pubkey_cert:validate_names/6 in lib/public_key/src/pubkey_cert.erl only checks SAN DNS entries against nameConstraints. Per RFC 5280, a permitted DNS subtree only restricts certificates that contain a DNS-typed name. A leaf with no subjectAltName therefore trivially satisfies any permitted;DNS:... constraint regardless of its subject commonName.\n\nSecond, public_key:pkix_verify_hostname/3 in lib/public_key/src/public_key.erl falls back to the subject commonName when no subjectAltName is present, extracting id-at-commonName attributes as presented IDs and matching them against the reference hostname. The strict pkix_verify_hostname_match_fun(https) matcher does not suppress this fallback.\n\nThe result is that path validation accepts a CN-only leaf under a DNS-constrained intermediate (no SAN means the nameConstraints are not triggered), and hostname verification then accepts it via the CN fallback. The bypass is reachable from stock ssl:connect with verify_peer, a trusted CA, SNI, and the canonical strict https hostname matcher.\n\nThis issue affects OTP from OTP 19.3 before OTP 29.0.1, OTP 28.5.0.1, OTP 27.3.4.12 and OTP 26.2.5.21, corresponding to public_key from 1.4 before 1.21.1, 1.20.3.1, 1.17.1.3 and 1.15.1.7.",
      "affected": [
        {
          "vendor": "Erlang",
          "product": "OTP",
          "packageName": "public_key",
          "defaultStatus": "unknown",
          "versions": [
            {
              "version": "1.4",
              "status": "affected",
              "versionType": "otp",
              "lessThan": "*",
              "changes": [
                {
                  "at": "1.15.1.7",
                  "status": "unaffected"
                },
                {
                  "at": "1.17.1.3",
                  "status": "unaffected"
                },
                {
                  "at": "1.20.3.1",
                  "status": "unaffected"
                },
                {
                  "at": "1.21.1",
                  "status": "unaffected"
                }
              ]
            }
          ]
        },
        {
          "vendor": "Erlang",
          "product": "OTP",
          "packageName": "erlang/otp",
          "collectionURL": "https://github.com",
          "defaultStatus": "unknown",
          "versions": [
            {
              "version": "19.3",
              "status": "affected",
              "versionType": "otp",
              "lessThan": "*",
              "changes": [
                {
                  "at": "26.2.5.21",
                  "status": "unaffected"
                },
                {
                  "at": "27.3.4.12",
                  "status": "unaffected"
                },
                {
                  "at": "28.5.0.1",
                  "status": "unaffected"
                },
                {
                  "at": "29.0.1",
                  "status": "unaffected"
                }
              ]
            },
            {
              "version": "b0c245e8132bb13171e277b1af59c0cec00c9459",
              "status": "affected",
              "versionType": "git",
              "lessThan": "*",
              "changes": [
                {
                  "at": "0769050c69d73762672b0db1347b6993a5b31759",
                  "status": "unaffected"
                },
                {
                  "at": "fb67c6d1836f51105a96d8b769e71e4215a79457",
                  "status": "unaffected"
                },
                {
                  "at": "21abed64eb2026b5f82f432709e4e932f9be389a",
                  "status": "unaffected"
                }
              ]
            }
          ]
        }
      ]
    }
  }
}