« Volver al listado

CVE-2026-42790

Estado: ModificadaAlta (7.6)—

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.

Two 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):

First, pubkey_cert:validate_names/6 in lib/public_key/src/pubkey_cert.erl only checks SAN DNS entries against nameConstraints.

Leer descripción completaMostrar menos

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.

Second, 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.

The 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.

This 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.

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

Vector CVSS requiere UI:P (interacción del usuario) en contexto de cliente TLS. La vulnerabilidad permite un MITM impersonando certificados válidos mediante bypass de nameConstraints (CWE-295, CWE-297), afectando a clientes OTP que aceptan conexiones fraudulentas.

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

User TrainingApplication Developer GuidanceActive Directory ConfigurationUser Account ManagementPrivileged Account ManagementPassword Policies

Tecnologías afectadas (1)

Erlang — Erlang/otp

CWE

Referencias

JSON original (NVD)

Mostrar
{
  "id": "CVE-2026-42790",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-42790",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-05-27T00:00:00+00:00"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 8.1,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N",
          "integrityImpact": "HIGH",
          "userInteraction": "REQUIRED",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.2,
        "exploitabilityScore": 2.8
      },
      {
        "type": "Secondary",
        "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.4,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "HIGH",
          "availabilityImpact": "NONE",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.2,
        "exploitabilityScore": 2.2
      }
    ],
    "cvssMetricV40": [
      {
        "type": "Secondary",
        "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "cvssData": {
          "Safety": "NOT_DEFINED",
          "version": "4.0",
          "Recovery": "NOT_DEFINED",
          "baseScore": 7.6,
          "Automatable": "NOT_DEFINED",
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "exploitMaturity": "NOT_DEFINED",
          "providerUrgency": "NOT_DEFINED",
          "userInteraction": "PASSIVE",
          "attackComplexity": "HIGH",
          "attackRequirements": "PRESENT",
          "privilegesRequired": "NONE",
          "subIntegrityImpact": "NONE",
          "vulnIntegrityImpact": "HIGH",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "vulnAvailabilityImpact": "NONE",
          "availabilityRequirement": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "subConfidentialityImpact": "NONE",
          "vulnConfidentialityImpact": "HIGH",
          "confidentialityRequirement": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "vulnerabilityResponseEffort": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED"
        }
      }
    ]
  },
  "affected": [
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "affectedData": [
        {
          "cpes": [
            "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"
          ],
          "repo": "https://github.com/erlang/otp",
          "vendor": "Erlang",
          "modules": [
            "pubkey_cert",
            "public_key"
          ],
          "product": "OTP",
          "versions": [
            {
              "status": "affected",
              "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"
                }
              ],
              "version": "1.4",
              "lessThan": "*",
              "versionType": "otp"
            }
          ],
          "packageURL": "pkg:otp/public_key?repository_url=https:%2F%2Fgithub.com%2Ferlang%2Fotp&vcs_url=git%20https:%2F%2Fgithub.com%2Ferlang%2Fotp.git",
          "packageName": "public_key",
          "programFiles": [
            "src/pubkey_cert.erl",
            "src/public_key.erl"
          ],
          "defaultStatus": "unknown",
          "programRoutines": [
            {
              "name": "pubkey_cert:validate_names/6"
            },
            {
              "name": "public_key:pkix_verify_hostname/3"
            }
          ]
        },
        {
          "cpes": [
            "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"
          ],
          "repo": "https://github.com/erlang/otp",
          "vendor": "Erlang",
          "modules": [
            "pubkey_cert",
            "public_key"
          ],
          "product": "OTP",
          "versions": [
            {
              "status": "affected",
              "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": "19.3",
              "lessThan": "*",
              "versionType": "otp"
            },
            {
              "status": "affected",
              "changes": [
                {
                  "at": "0769050c69d73762672b0db1347b6993a5b31759",
                  "status": "unaffected"
                },
                {
                  "at": "fb67c6d1836f51105a96d8b769e71e4215a79457",
                  "status": "unaffected"
                },
                {
                  "at": "21abed64eb2026b5f82f432709e4e932f9be389a",
                  "status": "unaffected"
                }
              ],
              "version": "b0c245e8132bb13171e277b1af59c0cec00c9459",
              "lessThan": "*",
              "versionType": "git"
            }
          ],
          "packageURL": "pkg:github/erlang/otp",
          "packageName": "erlang/otp",
          "programFiles": [
            "lib/public_key/src/pubkey_cert.erl",
            "lib/public_key/src/public_key.erl"
          ],
          "collectionURL": "https://github.com",
          "defaultStatus": "unknown",
          "programRoutines": [
            {
              "name": "pubkey_cert:validate_names/6"
            },
            {
              "name": "public_key:pkix_verify_hostname/3"
            }
          ]
        }
      ]
    },
    {
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
      "affectedData": [
        {
          "cpes": [
            "cpe:/a:redhat:openstack:16.2::el8"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat OpenStack Platform 16.2",
          "versions": [
            {
              "status": "unaffected",
              "version": "0:23.3.4.18-2.el8ost",
              "lessThan": "*",
              "versionType": "rpm"
            }
          ],
          "packageName": "erlang",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "defaultStatus": "affected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:openstack:18.0::el9"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat OpenStack Services on OpenShift 18.0",
          "versions": [
            {
              "status": "unaffected",
              "version": "0:26.2.5.21-2.el9ost",
              "lessThan": "*",
              "versionType": "rpm"
            }
          ],
          "packageName": "erlang",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "defaultStatus": "affected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:hummingbird:1"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat Hardened Images",
          "packageName": "erlang27",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "defaultStatus": "affected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:openstack:17.1"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat OpenStack Platform 17.1",
          "packageName": "erlang",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-05-27T17:16:36.030",
  "references": [
    {
      "url": "https://cna.erlef.org/cves/CVE-2026-42790.html",
      "tags": [
        "Third Party Advisory"
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://github.com/erlang/otp/commit/0769050c69d73762672b0db1347b6993a5b31759",
      "tags": [
        "Patch"
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://github.com/erlang/otp/commit/21abed64eb2026b5f82f432709e4e932f9be389a",
      "tags": [
        "Patch"
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://github.com/erlang/otp/commit/fb67c6d1836f51105a96d8b769e71e4215a79457",
      "tags": [
        "Patch"
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://github.com/erlang/otp/security/advisories/GHSA-22cw-4ph4-6447",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-42790",
      "tags": [
        "Mitigation",
        "Third Party Advisory"
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://www.erlang.org/doc/system/versions.html#order-of-versions",
      "tags": [
        "Product"
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    },
    {
      "url": "https://access.redhat.com/errata/RHSA-2026:39809",
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"
    },
    {
      "url": "https://access.redhat.com/errata/RHSA-2026:54757",
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"
    },
    {
      "url": "https://access.redhat.com/security/cve/CVE-2026-42790",
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"
    },
    {
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2482286",
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"
    },
    {
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42790.json",
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "description": [
        {
          "lang": "en",
          "value": "CWE-295"
        },
        {
          "lang": "en",
          "value": "CWE-297"
        }
      ]
    },
    {
      "type": "Secondary",
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
      "description": [
        {
          "lang": "en",
          "value": "CWE-295"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "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."
    }
  ],
  "lastModified": "2026-09-18T13:18:22.680",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "245CC08C-EB1F-4230-8F4B-98CFFB623EB2",
              "versionEndExcluding": "26.2.5.21",
              "versionStartIncluding": "19.3"
            },
            {
              "criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "91269F6D-B8A3-41F2-871C-79EBB9460BE8",
              "versionEndExcluding": "27.3.4.12",
              "versionStartIncluding": "27.0"
            },
            {
              "criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "844A3F01-AF3C-4C48-81DB-932B803D22C4",
              "versionEndExcluding": "28.5.0.1",
              "versionStartIncluding": "28.0"
            },
            {
              "criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "46976598-817C-4E93-AC4B-46434746C25F",
              "versionEndExcluding": "29.0.1",
              "versionStartIncluding": "29.0"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
}