CVE-2026-44435
Quicly: Remote Denial of Service via assertion failure when CRYPTO stream handshake data exceeds 32KB
CVSS Score
7.5
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-617 CWE-400 |
| Vendor | h2o |
| Product | quicly |
| Published | Jul 16, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Affected Versions
h2o / quicly
< 937d0e9