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Vulnerabilities

Vulnerability · CVE-2026-91767

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 c

Published Sep 25, 2026 · catalog updated Oct 28, 2026 · php_openssl_matches_wildcard_name() in ext/openssl/xp_ssl.c underflows

Last checked Oct 28, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-91767. EPSS is 0.11%. Act only if a listed version of php_openssl_matches_wildcard_name() in ext/openssl/xp_ssl.c underflows is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (php_openssl_matches_wildcard_name() in ext/openssl/xp_ssl.c underflows).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium6.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.11%
Remediation
Advisory link
Affected products
Debian:12 php8.2 · Debian:13 php8.4 · Debian:14 php8.4

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Debian:12 php8.20 → 8.2.34-1~deb12u1
  • Debian:13 php8.40 → 8.4.26-1~deb13u1
  • Debian:14 php8.40 → 8.4.26-1

How to fix CVE-2026-91767

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-91767. EPSS is 0.11%. Act only if a listed version of php_openssl_matches_wildcard_name() in ext/openssl/xp_ssl.c underflows is installed.

Which versions are affected?

Compare what you have installed with 0 → 8.2.34-1~deb12u1, 0 → 8.4.26-1~deb13u1, 0 → 8.4.26-1. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.11%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Debian security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Sep 25, 2026 · OpenSSF OSV / OSV Scanner

    Detected

    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 fro

  2. Oct 28, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    php8.2 fixed in 8.2.34-1~deb12u1; php8.4 fixed in 8.4.26-1~deb13u1; php8.4 fixed in 8.4.26-1

  3. Oct 28, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    php8.2 fixed in 8.2.34-1~deb12u1

  4. Oct 28, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    php8.4 fixed in 8.4.26-1~deb13u1

  5. Oct 28, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    php8.4 fixed in 8.4.26-1

  6. Oct 28, 2026 · OpenSSF OSV / OSV Scanner

    Updated

    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 fro

Sources

References

Freshness

Last verified in this catalog Oct 28, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • CVE.orgOct 28, 2026
  • FIRST EPSSOct 28, 2026
  • OpenSSF OSV / OSV ScannerOct 28, 2026