CVE-2025-61684
7.5 · HIGHOverview
CVE-2025-61684 is a high-severity vulnerability affecting h2o quicly. It was published on January 19, 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, an IETF QUIC protocol implementation, is susceptible to a denial-of-service attack prior to commit d9d3df6a8530a102b57d840e39b0311ce5c9e14e. A remote attacker can exploit these bugs to trigger an assertion failure that crashes process using Quicly. Commit d9d3df6a8530a102b57d840e39b0311ce5c9e14e fixes the issue.
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, < 2026-01-18 | Affected |
Frequently Asked Questions
What is CVE-2025-61684?
CVE-2025-61684 is a high-severity vulnerability affecting h2o quicly. It was published on January 19, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).
How severe is CVE-2025-61684?
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-2025-61684?
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-2025-61684?
CyberStrike's AI-powered security agents can automatically detect CVE-2025-61684 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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