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CVE-2025-61684

Quicly has assertion failures

Published: Jan 19, 2026Updated: Feb 27, 2026 Sources: CVE List NVDCWE-20
NVD MITRE
7.5CVSSHIGH
EPSS Score
0.3%
Top 75.2%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

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.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:NA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:HAvailability
High
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Weaknesses

CWE-20CWE-617

Affected Products

quiclyh2o
On-prem
Networking Infrastructure / load-balancer-proxy
h2ooss-projectNetworking Infrastructureaka h2o web server, h2o, picotls, quicly

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available

MITRE ATT&CK

2 techniques
Impact
Initial Access
View detailed technique mapping

References

https://github.com/h2o/quicly/commit/d9d3df6a8530a102b57d840e39b0311ce5c9e14e
github.com
https://github.com/h2o/quicly/security/advisories/GHSA-wr3c-345m-43v9
github.com

Timeline

Published
Jan 19, 2026
Last Updated
Feb 27, 2026

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