Denial of Service Vulnerability in Quicly by H2O
CVE-2025-61684

7.5HIGH

Key Information:

Vendor

H2o

Status
Quicly
Vendor
CVE Published:
19 January 2026

What is CVE-2025-61684?

Quicly, an implementation of the IETF QUIC protocol, is vulnerable to a denial-of-service attack that could allow a remote attacker to crash processes utilizing the protocol. This vulnerability is caused by certain assertion failures, which can be triggered through malicious inputs. The issue has been addressed in a fix available in commit d9d3df6a8530a102b57d840e39b0311ce5c9e14e, emphasizing the importance of updating to this secure version to mitigate the risk.

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Deploy the Patch

Affected Version(s)

quicly < d9d3df6

References

https://github.com/h2o/quicly/security/advisories/GHSA-wr...
x_refsource_CONFIRM
https://github.com/h2o/quicly/commit/d9d3df6a8530a102b57d...
x_refsource_MISC

CVSS V3.1

Score:
7.5
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

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