CVE-2026-44435
7.5 · HIGHOverview
CVE-2026-44435 is a high-severity vulnerability affecting h2o quicly. It was published on July 16, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).
This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical 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.
Remediation
Check the references section for vendor advisories and patches from h2o. Update quicly to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| h2o | quicly | >= 0, < 2026-05-29 | Affected |
Frequently Asked Questions
What is CVE-2026-44435?
CVE-2026-44435 is a high-severity vulnerability affecting h2o quicly. It was published on July 16, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).
How severe is CVE-2026-44435?
This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-44435?
Check the references section for vendor advisories and patches from h2o. Update quicly to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-44435?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-44435 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
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