5.9

CVE-2026-44452

h2o is vulnerable to heap overrun

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.
Daten sind bereitgestellt durch National Vulnerability Database (NVD)
H2o ≫ H2o Version < 2026-05-29
VulnDex Vulnerability Enrichment
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Zu dieser CVE wurde keine Warnung gefunden.
EPSS Metriken
Typ Quelle Score Percentile
EPSS FIRST.org 0.25% 0.163
CVSS Metriken
Quelle Base Score Exploit Score Impact Score Vector String
security-advisories@github.com 5.9 2.2 3.6
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE-125 Out-of-bounds Read

The product reads data past the end, or before the beginning, of the intended buffer.

CWE-170 Improper Null Termination

The product does not terminate or incorrectly terminates a string or array with a null character or equivalent terminator.

https://github.com/h2o/h2o/commit/8dc37cb1e6171f7f772667618ea440696fed82c3
Patch
https://github.com/h2o/h2o/security/advisories/GHSA-w68q-rqwx-7wvq
Vendor Advisory