Name-Constraint Inconsistency in RFC 5280 Implementation

{
  "id": "f2135eea17cc0667771011ffe18435a63f1a863f73f770f62968a1927d488ca4",
  "url": "https://kb.cert.org/vuls/id/573195",
  "method": "llm",
  "payload": {
    "kind": "advisory",
    "title": "Name-Constraint Inconsistency in RFC 5280 Implementation",
    "summary": "The note describes differing TLS-library behavior when validating X.509 Name Constraints, including defects and areas RFC 5280 does not fully specify. Exploitation requires a trusted signature over chosen certificate fields, an affected validation path, and an application that uses the accepted identity for authorization.",
    "evidence": "This note covers differences in how TLS libraries interpret X.509 Name Constraints.",
    "products": [
      {
        "name": {
          "value": "Go's crypto/x509",
          "evidence": "Go's crypto/x509"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      },
      {
        "name": {
          "value": "Apple's Security.framework",
          "evidence": "Apple's Security.framework"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      },
      {
        "name": {
          "value": "OpenSSL",
          "evidence": "OpenSSL*"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      },
      {
        "name": {
          "value": "LibreSSL",
          "evidence": "LibreSSL"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      },
      {
        "name": {
          "value": "pyca/cryptography",
          "evidence": "pyca/cryptography"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      },
      {
        "name": {
          "value": "wolfSSL",
          "evidence": "wolfSSL"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "fixed_cves": [],
    "related_cves": [
      {
        "value": "CVE-2026-3833",
        "evidence": "GnuTLS compared some names' case-sensitivity at the time of reporting (CVE-2026-3833, later fixed in 3.8.13)."
      },
      {
        "value": "CVE-2026-34073",
        "evidence": "pyca/cryptography checked DNS Name Constraints against certificate SANs but not the requested peer name (CVE-2026-34073, fixed in 46.0.6), as described in the linked vendor advisory."
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "official-cert-cc-vulnerability-notes",
  "document_id": 23367,
  "published_at": "2026-10-13T18:27:20.433+00:00"
}