Vulnerability · Published Jan 19, 2026 · Assigned by GitHub_M
CVE-2025-61684Quicly has assertion failures
High 7.5
In plain English
A high-severity improper input validation in quicly from h2o. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 34% of all known vulnerabilities).
Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.4%top 66.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official 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.
Affected products (as reported)
Weakness: CWE-20 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
References
- https://github.com/h2o/quicly/security/advisories/GHSA-wr3c-345m-43v9 x_refsource_CONFIRM
- https://github.com/h2o/quicly/commit/d9d3df6a8530a102b57d840e39b0311ce5c9e14e x_refsource_MISC