TLS Hostname Verification Falls Back to CN After SAN Mismatch
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.
CVE-2026-91769
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-91769
PHP
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"vendor": "PHP Group",
"product": "PHP",
"versions": [
{
"status": "affected",
"version": "8.2.*",
"lessThan": "8.2.34",
"versionType": "semver"
},
{
"status": "affected",
"version": "8.3.*",
"lessThan": "8.3.35",
"versionType": "semver"
},
{
"status": "affected",
"version": "8.4.*",
"lessThan": "8.4.26",
"versionType": "semver"
},
{
"status": "affected",
"version": "8.5.*",
"lessThan": "8.5.11",
"versionType": "semver"
}
],
"packageName": "ext-openssl",
"defaultStatus": "unaffected"
}
]- Related CVEs
- CVE-2026-91769
Source reference:
/cveMetadata/cveId
Publisher severity
medium
Source reference: /containers/cna/metrics
- Event
- #8520 · Revision 1
- Added to Heist Feed
- Publisher date