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.
Published: 2026-07-16
Score: 7.5 High
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
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Remediation

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History

Fri, 17 Jul 2026 00:45:00 +0000

Type Values Removed Values Added
First Time appeared H2o
H2o quicly
Vendors & Products H2o
H2o quicly

Thu, 16 Jul 2026 23:00:00 +0000

Type Values Removed Values Added
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.
Title Quicly: Remote Denial of Service via assertion failure when CRYPTO stream handshake data exceeds 32KB
Weaknesses CWE-400
CWE-617
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Subscriptions

H2o Quicly
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-07-16T22:39:50.873Z

Reserved: 2026-05-06T14:40:00.954Z

Link: CVE-2026-44435

cve-icon Vulnrichment

No data.

cve-icon NVD

No data.

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-07-17T00:30:03Z

Weaknesses