CVE-2026-44435: high-severity vulnerability in h2o quicly
Quicly: Remote Denial of Service via assertion failure when CRYPTO stream handshake data exceeds 32KB
Published · Updated
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21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.5epss 0.5%
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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Affected products
h2o · quiclyRelated CVEs — h2o quicly
In the same product, most dangerous first.
CVE-2024-45396HIGHQuicly assertion failuresEPSS 0.6%CVE-2026-44436HIGHQuicly is vulnerable to connection state corruptionEPSS 0.5%CVE-2026-44433MEDIUMQuicly is vulnerable to memory exhaustionEPSS 0.5%CVE-2025-61684HIGHQuicly has assertion failuresEPSS 0.4%CVE-2026-44434MEDIUMQuicly is vulnerable to stateless reset injectionEPSS 0.2%