CVE-2026-44435
High
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.
SeverityHigh
CVSS7.5
Exploit probability—
Product
H2o Quicly
PublishedJul 16, 2026
First seenJul 16, 2026
How to fix
Update
- h2o quicly2026-05-29 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| h2o quicly | v < 2026-05-29 | 2026-05-29 |
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