TLS Hostname Verification Falls Back to CN After SAN Mismatch (CVE-2026-91769) | HOL Guard CVE

Medium · CVSS 4.3CVE-2026-91769

TLS Hostname Verification Falls Back to CN After SAN Mismatch

Answer in brief

CVE-2026-91769 records a Medium severity (CVSS 4.3) vulnerability in TLS Hostname Verification Falls Back to CN After SAN Mismatch. The current sources do not mark it as known exploited. The current feed maps PHP Group/PHP (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 25, 2026Updated Sep 25, 2026Source checked Sep 25, 2026First seen by HOL Sep 25, 2026Material review Sep 25, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 4.3
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 4.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps PHP Group/PHP (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
PHP Group/PHPgeneric	>=8.2.* <8.2.34 \|\| >=8.3.* <8.3.35 \|\| >=8.4.* <8.4.26 \|\| >=8.5.* <8.5.11	8.2.34, 8.3.35, 8.4.26, 8.5.11

Recommended response

Check inventory. Check lockfiles and deployed manifests for PHP Group/PHP.
Review the reported fix. Update PHP Group/PHP to 8.2.34 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 25, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 25, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 25, 2026

Sources and claim methodology

GitHub security advisorygithub.com

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.