CVE-2026-44435

HIGH

Quicly: Remote Denial of Service via assertion failure when CRYPTO stream handshake data exceeds 32KB

Title source: cna
STIX 2.1

Description

Quicly is an IETF QUIC protocol implementation intended primarily for use within the H2O HTTP server. Prior to commit 937d0e9, an assertion failure is raised when the total number of valid handshake messages received over a CRYPTO stream of a single packet number space exceeds 32KB, causing a Denial of Service. This issue has been fixed by commit 937d0e9.

References (2)

Core 2

Scores

CVSS v3 7.5
EPSS 0.0028
EPSS Percentile 20.1%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CISA SSVC

Vulnrichment
Exploitation none
Automatable yes
Technical Impact partial

Details

CWE
CWE-400 CWE-617
Status published
Products (1)
h2o/quicly < 937d0e9
Published Jul 16, 2026
Tracked Since Jul 17, 2026