CVE-2026-33810 (GCVE-0-2026-33810)

Vulnerability from cvelistv5 – Published: 2026-04-08 01:06 – Updated: 2026-04-08 01:06
VLAI?
Title
Case-sensitive excludedSubtrees name constraints cause Auth Bypass in crypto/x509
Summary
When verifying a certificate chain containing excluded DNS constraints, these constraints are not correctly applied to wildcard DNS SANs which use a different case than the constraint. This only affects validation of otherwise trusted certificate chains, issued by a root CA in the VerifyOptions.Roots CertPool, or in the system certificate pool.
Severity ?
No CVSS data available.
CWE
  • CWE-295 - Improper Certificate Validation
Assigner
Go
References
Impacted products
Vendor Product Version
Go standard library crypto/x509 Affected: 1.26.0-0 , < 1.26.2 (semver)
Create a notification for this product.
Credits
Riyas from Saintgits College of Engineering k1rnt @1seal
Show details on NVD website
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "collectionURL": "https://pkg.go.dev",
          "defaultStatus": "unaffected",
          "packageName": "crypto/x509",
          "product": "crypto/x509",
          "programRoutines": [
            {
              "name": "newDNSConstraints"
            },
            {
              "name": "dnsConstraints.query"
            },
            {
              "name": "Certificate.Verify"
            }
          ],
          "vendor": "Go standard library",
          "versions": [
            {
              "lessThan": "1.26.2",
              "status": "affected",
              "version": "1.26.0-0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "value": "Riyas from Saintgits College of Engineering"
        },
        {
          "lang": "en",
          "value": "k1rnt"
        },
        {
          "lang": "en",
          "value": "@1seal"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "When verifying a certificate chain containing excluded DNS constraints, these constraints are not correctly applied to wildcard DNS SANs which use a different case than the constraint. This only affects validation of otherwise trusted certificate chains, issued by a root CA in the VerifyOptions.Roots CertPool, or in the system certificate pool."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "description": "CWE-295: Improper Certificate Validation",
              "lang": "en"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-04-08T01:06:56.546Z",
        "orgId": "1bb62c36-49e3-4200-9d77-64a1400537cc",
        "shortName": "Go"
      },
      "references": [
        {
          "url": "https://go.dev/cl/763763"
        },
        {
          "url": "https://go.dev/issue/78332"
        },
        {
          "url": "https://groups.google.com/g/golang-announce/c/0uYbvbPZRWU"
        },
        {
          "url": "https://pkg.go.dev/vuln/GO-2026-4866"
        }
      ],
      "title": "Case-sensitive excludedSubtrees name constraints cause Auth Bypass in crypto/x509"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "1bb62c36-49e3-4200-9d77-64a1400537cc",
    "assignerShortName": "Go",
    "cveId": "CVE-2026-33810",
    "datePublished": "2026-04-08T01:06:56.546Z",
    "dateReserved": "2026-03-23T20:35:32.814Z",
    "dateUpdated": "2026-04-08T01:06:56.546Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-33810\",\"sourceIdentifier\":\"security@golang.org\",\"published\":\"2026-04-08T02:16:03.950\",\"lastModified\":\"2026-04-08T21:26:35.910\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"When verifying a certificate chain containing excluded DNS constraints, these constraints are not correctly applied to wildcard DNS SANs which use a different case than the constraint. This only affects validation of otherwise trusted certificate chains, issued by a root CA in the VerifyOptions.Roots CertPool, or in the system certificate pool.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://go.dev/cl/763763\",\"source\":\"security@golang.org\"},{\"url\":\"https://go.dev/issue/78332\",\"source\":\"security@golang.org\"},{\"url\":\"https://groups.google.com/g/golang-announce/c/0uYbvbPZRWU\",\"source\":\"security@golang.org\"},{\"url\":\"https://pkg.go.dev/vuln/GO-2026-4866\",\"source\":\"security@golang.org\"}]}}"
  }
}


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