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Vulnerability record · CVE-2026-91767 · published 25 September 2026

CVE-2026-91767: Php heap-based buffer overflow vulnerability

Php · Php

php_openssl_matches_wildcard_name() in ext/openssl/xp_ssl.c underflows the length argument passed to memchr() when a TLS server certificate presents a wildcard name whose literal characters are together longer than the hostname being verified. A malicious server presenting such a certificate makes the PHP client read up to SIZE_MAX bytes past the end of a heap allocation. The path is reachable from any default client stream, because verify_peer_name is enabled by default.

6.5 CVSS 3.1 Medium EPSS 0.11% · top 98.8% CWE-122 · Heap-based buffer overflow
6.5CVSS 3.1 base score
0.11%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
1References
27 Oct 2026Last modified by NVD

Description

php_openssl_matches_wildcard_name() in ext/openssl/xp_ssl.c underflows the length argument passed to memchr() when a TLS server certificate presents a wildcard name whose literal characters are together longer than the hostname being verified. A malicious server presenting such a certificate makes the PHP client read up to SIZE_MAX bytes past the end of a heap allocation. The path is reachable from any default client stream, because verify_peer_name is enabled by default.

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/php/php-src/security/advisories/GHSA-xr7j-rvgx-xq5p Vendor Advisory

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-91767), CISA KEV, FIRST EPSS (scores of 2026-11-14). This page is refreshed as NVD updates the record.