Host impersonation via SAN-to-CN fallback
Published Sep 25, 2026 · Updated Sep 25, 2026
Improper TLS hostname verification in PHP 8.2 through 8.5 allows man-in-the-middle attackers to impersonate trusted hosts. php_openssl_apply_peer_verification_policy() checks subjectAltName identities but consults the Common Name whenever none matches the requested peer_name. Exploitation requires a client-trusted certificate and a network-path position, enabling intercepted PHP TLS clients to accept the wrong host.
Summary
What happened
Improper TLS hostname verification in PHP 8.2 through 8.5 allows man-in-the-middle attackers to impersonate trusted hosts. php_openssl_apply_peer_verification_policy() checks subjectAltName identities but consults the Common Name whenever none matches the requested peer_name. Exploitation requires a client-trusted certificate and a network-path position, enabling intercepted PHP TLS clients to accept the wrong host.
The record
- CVE
- CVE-2026-91769
- Published
- Sep 25, 2026
- Updated
- Sep 25, 2026
- Vendor
- PHP Development Team
- Product
- PHP
- Classifications
- T1557
- Attack vector
- adjacent
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 25, 2026CVE publishedPublication date reported by the CVE source.
- Sep 25, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=8.2.* <8.2.34
- Affected versionversion=8.3.* <8.3.35
- Affected versionversion=8.4.* <8.4.26
- Affected versionversion=8.5.* <8.5.11
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
Public exploit references
- GHSA-vvx9-73fr-5jjx certificate-verification proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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