Vulnerability-Lookup

(CVE-2026-27138)

Vulnerability from cleanstart – Published: 2026-10-06 00:36 – Updated: 2026-10-08 15:18 – Source website

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

Details

Security vulnerability affects the temporal-server package. 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.

Severity

5.9 (Medium)


                    
                      CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

References

URL

Type

	https://github.com/cleanstart-dev/cleanstart-secu…	ADVISORY
	https://osv.dev/vulnerability/CVE-2026-27138	WEB
	https://nvd.nist.gov/vuln/detail/CVE-2026-27138	WEB

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "CleanStart",
        "name": "temporal-server",
        "purl": "pkg:apk/cleanstart/temporal-server"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.31.3-r3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "credits": [],
  "database_specific": {},
  "details": "Security vulnerability affects the temporal-server package. 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.",
  "id": "CLEANSTART-2026-NA69133",
  "modified": "2026-10-08T15:18:11Z",
  "published": "2026-10-06T00:36:15.021883Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/cleanstart-dev/cleanstart-security-advisories/tree/main/advisories/2026/CLEANSTART-2026-NA69133.json"
    },
    {
      "type": "WEB",
      "url": "https://osv.dev/vulnerability/CVE-2026-27138"
    },
    {
      "type": "WEB",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27138"
    }
  ],
  "related": [],
  "schema_version": "1.7.3",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "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",
  "upstream": [
    "CVE-2026-27138"
  ]
}

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

Vulnerability from cvelistv5 – Published: 2026-03-06 21:28 – Updated: 2026-03-10 13:35

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

Go CNA under the Google root

CNA scorecard E 42/100 over 75 records in the last 180 days details

References

4 references

URL	Tags
https://groups.google.com/g/golang-announce/c/Edh…
https://go.dev/issue/77953
https://go.dev/cl/752183
https://pkg.go.dev/vuln/GO-2026-4600

Impacted products

1 product

Vendor	Product	Version
Go standard library	crypto/x509	Affected: 1.26.0-0 , < 1.26.1 (semver)

Credits

Jakub Ciolek

Show details on NVD website

JSON

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"
}

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.

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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