VDB-341792 · CVE-2025-61684 · GHSA-wr3c-345m-43v9

h2o quicly denial of service

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
6.3	$0-$5k	0.00

Summaryinfo

A vulnerability labeled as problematic has been found in h2o quicly. Affected by this vulnerability is an unknown functionality. Such manipulation leads to denial of service. This vulnerability is uniquely identified as CVE-2025-61684. The attack can be launched remotely. No exploit exists. Applying a patch is advised to resolve this issue.

Detailsinfo

A vulnerability was found in h2o quicly (the affected version unknown). It has been rated as problematic. Affected by this issue is an unknown part. The manipulation with an unknown input leads to a denial of service vulnerability. Using CWE to declare the problem leads to CWE-404. The product does not release or incorrectly releases a resource before it is made available for re-use. Impacted is availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2025-61684 since 09/29/2025. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1499.

Applying the patch d9d3df6a8530a102b57d840e39b0311ce5c9e14e is able to eliminate this problem. The bugfix is ready for download at github.com.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2025-206302). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Vendor

Name

quicly

License

open-source

Website

Product: https://github.com/h2o/quicly/

CPE 2.3info

🔒

CPE 2.2info

🔒

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.4
VulDB Meta Temp Score: 6.3

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.5
CNA Vector (GitHub_M): 🔒

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Denial of service
CWE: CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Patch
Status: 🔍

0-Day Time: 🔒

Patch: d9d3df6a8530a102b57d840e39b0311ce5c9e14e

Timelineinfo

09/29/2025 CVE reserved
01/19/2026 +112 days Advisory disclosed
01/19/2026 +0 days VulDB entry created
01/20/2026 +1 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: GHSA-wr3c-345m-43v9
Status: Confirmed

CVE: CVE-2025-61684 (🔒)
GCVE (CVE): GCVE-0-2025-61684
GCVE (VulDB): GCVE-100-341792
EUVD: 🔒

Entryinfo

Created: 01/19/2026 19:05
Updated: 01/20/2026 10:08
Changes: 01/19/2026 19:05 (64), 01/20/2026 10:08 (1)
Complete: 🔍
Cache ID: 216::103

VulDB is the best source for vulnerability data and more expert information about this specific topic.