CVEvulnerability
CVE-2026-44452
5.9 MEDIUM
Official page ↗
- Status
- Analyzed
- Published
- 2026-07-16
- Last modified
- 2026-08-06
- Assigner
- [email protected]
- CVSS 3.1 ([email protected])
- 5.9 MEDIUM — CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- Weaknesses
- CWE-125, CWE-170
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.
Affected configurations
• h2o h2o (< 2026-05-29)