Description
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.
Published: 2026-09-25
Score: 4.3 Medium
EPSS: < 1% Very Low
KEV: No
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Debian DSA Debian DSA DSA-6514-1 php8.4 security update
History

Tue, 29 Sep 2026 13:15:00 +0000

Type Values Removed Values Added
First Time appeared Redhat
Redhat hummingbird
Weaknesses CWE-295
CPEs cpe:/a:redhat:hummingbird:1
Vendors & Products Redhat
Redhat hummingbird
References
Metrics threat_severity

None

threat_severity

Moderate


Mon, 28 Sep 2026 14:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Sat, 26 Sep 2026 08:45:00 +0000

Type Values Removed Values Added
First Time appeared Php Group
Php Group php
Vendors & Products Php Group
Php Group php

Fri, 25 Sep 2026 21:15:00 +0000

Type Values Removed Values Added
Description 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.
Title TLS Hostname Verification Falls Back to CN After SAN Mismatch
Weaknesses CWE-297
References
Metrics cvssV3_1

{'score': 4.3, 'vector': 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: php

Published:

Updated: 2026-09-28T13:31:31.508Z

Reserved: 2026-09-15T00:44:10.816Z

Link: CVE-2026-91769

cve-icon Vulnrichment

Updated: 2026-09-28T13:24:43.572Z

cve-icon NVD

Status : Received

Published: 2026-09-25T21:17:24.913

Modified: 2026-09-28T14:17:23.180

Link: CVE-2026-91769

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-09-25T20:59:39Z

Links: CVE-2026-91769 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-09-26T08:30:02Z

Weaknesses