GCVE Workshop - 22 September 2026 (14:00-18:00), Luxembourg Before The Vulnopticon Conference - Registration

CVE-2026-27138 (GCVE-0-2026-27138)

Vulnerability from cvelistv5 – Published: 2026-03-06 21:28 – Updated: 2026-03-10 13:35
VLAI
Title
Panic in name constraint checking for malformed certificates in crypto/x509
Summary
Certificate verification can panic when a certificate in the chain has an empty DNS name and another certificate in the chain has excluded name constraints. This can crash programs that are either directly verifying X.509 certificate chains, or those that use TLS.
Severity
5.9 (Medium)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-03-10 13:34 UTC
CWE
  • CWE-1285 - Improper Validation of Specified Index, Position, or Offset in Input
Assigner
References
Impacted products
Vendor Product Version CPE status
Go standard library crypto/x509 Affected: 1.26.0-0 , < 1.26.1 (semver)
guessed Create a notification for this product.
Credits
Jakub Ciolek
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "cvssV3_1": {
              "attackComplexity": "HIGH",
              "attackVector": "NETWORK",
              "availabilityImpact": "HIGH",
              "baseScore": 5.9,
              "baseSeverity": "MEDIUM",
              "confidentialityImpact": "NONE",
              "integrityImpact": "NONE",
              "privilegesRequired": "NONE",
              "scope": "UNCHANGED",
              "userInteraction": "NONE",
              "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
              "version": "3.1"
            }
          },
          {
            "other": {
              "content": {
                "id": "CVE-2026-27138",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-03-10T13:34:15.972110Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-03-10T13:35:19.784Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "collectionURL": "https://pkg.go.dev",
          "defaultStatus": "unaffected",
          "packageName": "crypto/x509",
          "product": "crypto/x509",
          "programRoutines": [
            {
              "name": "dnsConstraints.query"
            },
            {
              "name": "Certificate.Verify"
            }
          ],
          "vendor": "Go standard library",
          "versions": [
            {
              "lessThan": "1.26.1",
              "status": "affected",
              "version": "1.26.0-0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "value": "Jakub Ciolek"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Certificate verification can panic when a certificate in the chain has an empty DNS name and another certificate in the chain has excluded name constraints. This can crash programs that are either directly verifying X.509 certificate chains, or those that use TLS."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "description": "CWE-1285: Improper Validation of Specified Index, Position, or Offset in Input",
              "lang": "en"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-03-08T05:56:21.000Z",
        "orgId": "1bb62c36-49e3-4200-9d77-64a1400537cc",
        "shortName": "Go"
      },
      "references": [
        {
          "url": "https://groups.google.com/g/golang-announce/c/EdhZqrQ98hk"
        },
        {
          "url": "https://go.dev/issue/77953"
        },
        {
          "url": "https://go.dev/cl/752183"
        },
        {
          "url": "https://pkg.go.dev/vuln/GO-2026-4600"
        }
      ],
      "title": "Panic in name constraint checking for malformed certificates in crypto/x509"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "1bb62c36-49e3-4200-9d77-64a1400537cc",
    "assignerShortName": "Go",
    "cveId": "CVE-2026-27138",
    "datePublished": "2026-03-06T21:28:14.000Z",
    "dateReserved": "2026-02-17T19:57:28.435Z",
    "dateUpdated": "2026-03-10T13:35:19.784Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-27138",
      "date": "2026-09-16",
      "epss": "0.0035",
      "percentile": "0.28454"
    },
    "microsoft_vex": {
      "current_release_date": "2026-03-14T01:37:26.000Z",
      "cve": "CVE-2026-27138",
      "id": "msrc_CVE-2026-27138",
      "initial_release_date": "2026-03-02T00:00:00.000Z",
      "product_status:fixed": "2",
      "product_status:known_affected": "2",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "Panic in name constraint checking for malformed certificates in crypto/x509",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-27138.json",
      "version": "2"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-27138\",\"sourceIdentifier\":\"security@golang.org\",\"published\":\"2026-03-06T22:16:00.963\",\"lastModified\":\"2026-06-17T10:26:44.093\",\"vulnStatus\":\"Analyzed\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"Certificate verification can panic when a certificate in the chain has an empty DNS name and another certificate in the chain has excluded name constraints. This can crash programs that are either directly verifying X.509 certificate chains, or those that use TLS.\"},{\"lang\":\"es\",\"value\":\"La verificaci\u00f3n de certificados puede entrar en p\u00e1nico cuando un certificado en la cadena tiene un nombre DNS vac\u00edo y otro certificado en la cadena tiene restricciones de nombre excluidas. Esto puede bloquear programas que est\u00e1n verificando directamente cadenas de certificados X.509, o aquellos que usan TLS.\"}],\"affected\":[{\"source\":\"security@golang.org\",\"affectedData\":[{\"vendor\":\"Go standard library\",\"product\":\"crypto/x509\",\"defaultStatus\":\"unaffected\",\"collectionURL\":\"https://pkg.go.dev\",\"packageName\":\"crypto/x509\",\"programRoutines\":[{\"name\":\"dnsConstraints.query\"},{\"name\":\"Certificate.Verify\"}],\"versions\":[{\"version\":\"1.26.0-0\",\"lessThan\":\"1.26.1\",\"versionType\":\"semver\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":5.9,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"HIGH\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":2.2,\"impactScore\":3.6}],\"ssvcV203\":[{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"ssvcData\":{\"timestamp\":\"2026-03-10T13:34:15.972110Z\",\"id\":\"CVE-2026-27138\",\"options\":[{\"exploitation\":\"none\"},{\"automatable\":\"no\"},{\"technicalImpact\":\"partial\"}],\"role\":\"CISA Coordinator\",\"version\":\"2.0.3\"}}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-295\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:golang:go:1.26.0:*:*:*:*:*:*:*\",\"matchCriteriaId\":\"A40FE3CB-0D03-462B-8A19-4DF1920ABE82\"}]}]}],\"references\":[{\"url\":\"https://go.dev/cl/752183\",\"source\":\"security@golang.org\",\"tags\":[\"Mailing List\"]},{\"url\":\"https://go.dev/issue/77953\",\"source\":\"security@golang.org\",\"tags\":[\"Issue Tracking\"]},{\"url\":\"https://groups.google.com/g/golang-announce/c/EdhZqrQ98hk\",\"source\":\"security@golang.org\",\"tags\":[\"Release Notes\"]},{\"url\":\"https://pkg.go.dev/vuln/GO-2026-4600\",\"source\":\"security@golang.org\",\"tags\":[\"Vendor Advisory\"]}]}}",
    "redhat_vex": {
      "aggregate_severity": "Low",
      "current_release_date": "2026-06-28T07:22:57+00:00",
      "cve": "CVE-2026-27138",
      "id": "CVE-2026-27138",
      "initial_release_date": "2026-03-06T21:28:14+00:00",
      "product_status:fixed": "4",
      "product_status:known_affected": "32",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "crypto/x509: Panic in name constraint checking for malformed certificates in crypto/x509",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27138.json",
      "version": "3"
    },
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 5.9, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"MEDIUM\", \"vectorString\": \"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H\", \"integrityImpact\": \"NONE\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"HIGH\", \"availabilityImpact\": \"HIGH\", \"privilegesRequired\": \"NONE\", \"confidentialityImpact\": \"NONE\"}}, {\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-27138\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-03-10T13:34:15.972110Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-03-10T13:35:03.116Z\"}}], \"cna\": {\"title\": \"Panic in name constraint checking for malformed certificates in crypto/x509\", \"credits\": [{\"lang\": \"en\", \"value\": \"Jakub Ciolek\"}], \"affected\": [{\"vendor\": \"Go standard library\", \"product\": \"crypto/x509\", \"versions\": [{\"status\": \"affected\", \"version\": \"1.26.0-0\", \"lessThan\": \"1.26.1\", \"versionType\": \"semver\"}], \"packageName\": \"crypto/x509\", \"collectionURL\": \"https://pkg.go.dev\", \"defaultStatus\": \"unaffected\", \"programRoutines\": [{\"name\": \"dnsConstraints.query\"}, {\"name\": \"Certificate.Verify\"}]}], \"references\": [{\"url\": \"https://groups.google.com/g/golang-announce/c/EdhZqrQ98hk\"}, {\"url\": \"https://go.dev/issue/77953\"}, {\"url\": \"https://go.dev/cl/752183\"}, {\"url\": \"https://pkg.go.dev/vuln/GO-2026-4600\"}], \"descriptions\": [{\"lang\": \"en\", \"value\": \"Certificate verification can panic when a certificate in the chain has an empty DNS name and another certificate in the chain has excluded name constraints. This can crash programs that are either directly verifying X.509 certificate chains, or those that use TLS.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"description\": \"CWE-1285: Improper Validation of Specified Index, Position, or Offset in Input\"}]}], \"providerMetadata\": {\"orgId\": \"1bb62c36-49e3-4200-9d77-64a1400537cc\", \"shortName\": \"Go\", \"dateUpdated\": \"2026-03-08T05:56:21.000Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-27138\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-03-10T13:35:19.784Z\", \"dateReserved\": \"2026-02-17T19:57:28.435Z\", \"assignerOrgId\": \"1bb62c36-49e3-4200-9d77-64a1400537cc\", \"datePublished\": \"2026-03-06T21:28:14.000Z\", \"assignerShortName\": \"Go\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.