CVE-2026-91769
MEDIUMDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 3% of all known CVEs.
References
Related Vulnerabilities
Other CWE-297 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2014-3522 | Medium | 4.0 | 5.6% | - | Fix |
| CVE-2018-10936 | High | 8.1 | 2.9% | - | Fix |
| CVE-2020-1887 | Critical | 9.1 | 1.6% | - | Fix |
| CVE-2024-2466 | Medium | 6.5 | 1.3% | - | Fix |
| CVE-2020-14387 | High | 7.4 | 1.1% | - | Fix |
| CVE-2020-15260 | Medium | 6.8 | 1.0% | - | Fix |
Common questions
How do I fix CVE-2026-91769?
Upgrade php8.2 on debian 12 to 8.2.34-1~deb12u1 or later.
Is CVE-2026-91769 being actively exploited?
Not that we know of. CVE-2026-91769 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.14% is the estimated probability that it will be exploited in the next 30 days. That is higher than 3% of all scored CVEs.
How severe is CVE-2026-91769?
CVE-2026-91769 has a CVSS v3 base score of 4.3, rated moderate. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-91769 affect?
Published advisories record a fix for php8.2 (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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Markdown
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-09-29.