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VULNERABILITIES

CVE-2026-44452 Details

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.

Metrics

CVSS 3.x Severity and Vector Strings:

CNA: [email protected]CVSS-B:5.9 MEDIUMVector:CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

References to Advisories, Solutions, and Tools

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URLSource(s)Tag(s)
https://github.com/h2o/h2o/commit/8dc37cb1e6171f7f772667618ea440696fed82c3 [email protected]Patch
https://github.com/h2o/h2o/security/advisories/GHSA-w68q-rqwx-7wvq [email protected]Vendor Advisory

Weakness Enumeration

CWE-IDCWE NameSource
CWE-125Out-of-bounds Read[email protected]
CWE-170Improper Null Termination[email protected]

Affected Products

ProductVersions
h2o h2o
< 2026-05-29

CPE

  • cpe:2.3:a:h2o:h2o:*:*:*:*:*:*:*:*

Remediation

  • No remediation found in references.

Change History

4 change records found show changes

QUICK INFO

CVE Dictionary Entry:
CVE-2026-44452
NVD Published Date:
Jul 16, 2026
NVD Last Modified:
Aug 6, 2026
Source:
[email protected]