CVE-2026-91769
Published: September 26, 2026Last modified: September 26, 2026
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.
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score | 4.3 |
| Attack Vector | ADJACENT_NETWORK |
| Attack complexity | LOW |
| Privileges required | NONE |
| User interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality | LOW |
| Integrity impact | NONE |
| Availability impact | NONE |
| Vector | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N |
Status
| Product | Release | Package | Status |
|---|---|---|---|
| Alpaquita Linux | 23 LTS | php81 | Unknown (8.1.19-r0) |
| 25 LTS | php83 | Fixed (8.3.35-r0) | |
| Stream | php83 | Fixed (8.3.35-r0) |