CVE-2026-44452
h2o is vulnerable to heap overrun
- State
- Published
- Severity
- 5.9 Medium
- Published
- Jul 16, 2026
- Updated
- Jul 17, 2026
- Reserved
- May 6, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 5.9 Medium | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H | GitHub_M |
Weaknesses
Affected Products
| Product | Versions |
|---|---|
h2oh2o |
|
References
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