VULNERABILITY INTELLIGENCE

CVE-2026-44452

CVSS score5.9 MEDIUM
EPSS probability0.41%
CISA KEVNot currently listed
Published2026-07-16
Last modified2026-08-06
CVSS vectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Description

h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. Prior to commit 8dc37cb, when h2o receives a ClientHello message over TLS or QUIC and it contains a zero-length SNI extension, the h2o server runs over the zero-length hostname while trying to copy the hostname, assuming that it is NULL-terminated. This is a potential denial-of-service attack vector in sense that it might trigger segmentation violation. This issue has been fixed by commit 8dc37cb.

Weakness classification

  • security-advisories@github.com: CWE-125

Primary references