Vulnerability-Lookup

Vulnerability from bitnami_vulndb

Published

2026-10-01 09:29

Modified

2026-10-01 09:55

Summary

TLS Hostname Verification Falls Back to CN After SAN Mismatch

Details

PHP's OpenSSL stream peer verification checks the certificate's subjectAltName entries first and, whenever no entry matches, falls back to the Common Name. RFC 6125 requires the CN to be ignored once the certificate presents any service identity, so a certificate carrying a non-matching DNS SAN was still accepted when its CN matched the requested peer_name. A certificate trusted by the client for one name can therefore be used to impersonate another.

JSON

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Bitnami",
        "name": "libphp",
        "purl": "pkg:bitnami/libphp"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "8.2.0"
            },
            {
              "fixed": "8.2.34"
            },
            {
              "introduced": "8.3.0"
            },
            {
              "fixed": "8.3.35"
            },
            {
              "introduced": "8.4.0"
            },
            {
              "fixed": "8.4.26"
            },
            {
              "introduced": "8.5.0"
            },
            {
              "fixed": "8.5.11"
            }
          ],
          "type": "SEMVER"
        }
      ],
      "severity": [
        {
          "score": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
          "type": "CVSS_V3"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-91769"
  ],
  "database_specific": {
    "cpes": [
      "cpe:2.3:a:php:php:*:*:*:*:*:*:*:*"
    ],
    "severity": "Medium"
  },
  "details": "PHP\u0027s OpenSSL stream peer verification checks the certificate\u0027s subjectAltName entries first and, whenever no entry matches, falls back to the Common Name. RFC 6125 requires the CN to be ignored once the certificate presents any service identity, so a certificate carrying a non-matching DNS SAN was still accepted when its CN matched the requested peer_name. A certificate trusted by the client for one name can therefore be used to impersonate another.",
  "id": "BIT-libphp-2026-91769",
  "modified": "2026-10-01T09:55:18.588Z",
  "published": "2026-10-01T09:29:27.354Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/php/php-src/security/advisories/GHSA-vvx9-73fr-5jjx"
    },
    {
      "type": "WEB",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-91769"
    }
  ],
  "schema_version": "1.6.2",
  "summary": "TLS Hostname Verification Falls Back to CN After SAN Mismatch"
}

CVE-2026-91769 (GCVE-0-2026-91769)

Vulnerability from cvelistv5 – Published: 2026-09-25 20:59 – Updated: 2026-10-04 16:10

Title

TLS Hostname Verification Falls Back to CN After SAN Mismatch

Summary

Severity

4.3 (Medium)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-28 12:56 UTC

CWE

CWE-297 - Improper validation of certificate with host mismatch

Assigner

php CNA under the mitre root

CNA scorecard B 80/100 over 25 records in the last 180 days details

References

1 reference

URL	Tags
https://github.com/php/php-src/security/advisorie…	vendor-advisory

Impacted products

1 product

Vendor	Product	Version
PHP Group	PHP	Affected: 8.2.* , < 8.2.34 (semver) Affected: 8.3.* , < 8.3.35 (semver) Affected: 8.4.* , < 8.4.26 (semver) Affected: 8.5.* , < 8.5.11 (semver)

Credits

Cantina (https://www.cantina.security/) David Korczynski Jakub Zelenka Arnaud Le Blanc Alexandre Daubois @benzdeus (GitHub)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-91769",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-09-28T12:56:47.310384Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-09-28T13:31:31.508Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "packageName": "ext-openssl",
          "product": "PHP",
          "vendor": "PHP Group",
          "versions": [
            {
              "lessThan": "8.2.34",
              "status": "affected",
              "version": "8.2.*",
              "versionType": "semver"
            },
            {
              "lessThan": "8.3.35",
              "status": "affected",
              "version": "8.3.*",
              "versionType": "semver"
            },
            {
              "lessThan": "8.4.26",
              "status": "affected",
              "version": "8.4.*",
              "versionType": "semver"
            },
            {
              "lessThan": "8.5.11",
              "status": "affected",
              "version": "8.5.*",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "reporter",
          "value": "Cantina (https://www.cantina.security/)"
        },
        {
          "lang": "en",
          "type": "reporter",
          "value": "David Korczynski"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "Jakub Zelenka"
        },
        {
          "lang": "en",
          "type": "remediation reviewer",
          "value": "Arnaud Le Blanc"
        },
        {
          "lang": "en",
          "type": "remediation reviewer",
          "value": "Alexandre Daubois"
        },
        {
          "lang": "en",
          "type": "reporter",
          "value": "@benzdeus (GitHub)"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003ePHP\u0027s OpenSSL stream peer verification checks the certificate\u0027s subjectAltName entries first and, whenever no entry matches, falls back to the Common Name. RFC 6125 requires the CN to be ignored once the certificate presents any service identity, so a certificate carrying a non-matching DNS SAN was still accepted when its CN matched the requested \u003ccode\u003epeer_name\u003c/code\u003e. A certificate trusted by the client for one name can therefore be used to impersonate another.\u003c/p\u003e"
            }
          ],
          "value": "PHP\u0027s OpenSSL stream peer verification checks the certificate\u0027s subjectAltName entries first and, whenever no entry matches, falls back to the Common Name. RFC 6125 requires the CN to be ignored once the certificate presents any service identity, so a certificate carrying a non-matching DNS SAN was still accepted when its CN matched the requested peer_name. A certificate trusted by the client for one name can therefore be used to impersonate another."
        }
      ],
      "impacts": [
        {
          "capecId": "CAPEC-94",
          "descriptions": [
            {
              "lang": "en",
              "value": "CAPEC-94"
            }
          ]
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "ADJACENT_NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 4.3,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "LOW",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
            "version": "3.1"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-297",
              "description": "CWE-297 Improper validation of certificate with host mismatch",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-04T16:10:05.639Z",
        "orgId": "dd77f84a-d19a-4638-8c3d-a322d820ed2b",
        "shortName": "php"
      },
      "references": [
        {
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://github.com/php/php-src/security/advisories/GHSA-vvx9-73fr-5jjx"
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "title": "TLS Hostname Verification Falls Back to CN After SAN Mismatch",
      "x_generator": {
        "engine": "Vulnogram 1.0.5"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "dd77f84a-d19a-4638-8c3d-a322d820ed2b",
    "assignerShortName": "php",
    "cveId": "CVE-2026-91769",
    "datePublished": "2026-09-25T20:59:39.727Z",
    "dateReserved": "2026-09-15T00:44:10.816Z",
    "dateUpdated": "2026-10-04T16:10:05.639Z",
    "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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