OpenSSL Stream Verification Flaw in PHP Affects Multiple Versions
CVE-2026-91769

4.3MEDIUM

Key Information:

Vendor

PHP Group

Status
PHP
Vendor
CVE Published:
25 September 2026

What is CVE-2026-91769?

The OpenSSL stream verification process in PHP contains a flaw where the peer verification checks prioritize the Common Name (CN) over the subjectAltName (SAN) entries. This scenario can lead to acceptance of potentially malicious certificates, allowing an attacker to impersonate a legitimate service. Despite RFC 6125 stipulating that any matching SAN should take precedence over the CN, the flawed implementation could enable exploitation of trusted certificates for unintended service identities.

Affected Version(s)

PHP 8.2.* < 8.2.34

PHP 8.3.* < 8.3.35

PHP 8.4.* < 8.4.26

References

https://github.com/php/php-src/security/advisories/GHSA-v...
vendor-advisory

CVSS V3.1

Score:
4.3
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
None
Availability:
Low
Attack Vector:
Adjacent Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

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