CVE-2026-21435

webtransport-go is an implementation of the WebTransport protocol. Prior to v0.10.0, an attacker can cause a denial of service in webtransport-go by preventing or indefinitely delaying WebTransport session closure. A malicious peer can withhold QUIC flow control credit on the CONNECT stream, blocking transmission of the WT_CLOSE_SESSION capsule and causing the close operation to hang. This vulnerability is fixed in v0.10.0.

CVSS v3 5.3 MEDIUM

5.3^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 3.9 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact LOW

Scope UNCHANGED

References

Link	Resource
https://github.com/quic-go/webtransport-go/releases/tag/v0.10.0	Product Release Notes
https://github.com/quic-go/webtransport-go/security/advisories/GHSA-px4r-g4p3-hhqv	Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:quic-go:webtransport-go:*:*:*:*:*:go:*:*

History

19 Feb 2026, 22:51

Type	Values Removed	Values Added
References	~~() https://github.com/quic-go/webtransport-go/releases/tag/v0.10.0 -~~	() https://github.com/quic-go/webtransport-go/releases/tag/v0.10.0 - Product, Release Notes
References	~~() https://github.com/quic-go/webtransport-go/security/advisories/GHSA-px4r-g4p3-hhqv -~~	() https://github.com/quic-go/webtransport-go/security/advisories/GHSA-px4r-g4p3-hhqv - Vendor Advisory
First Time		Quic-go webtransport-go Quic-go
CPE		cpe:2.3:a:quic-go:webtransport-go::::::go::*

12 Feb 2026, 19:15

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-02-12 19:15

Updated : 2026-02-19 22:51

NVD link : CVE-2026-21435

Mitre link : CVE-2026-21435

CVE.ORG link : CVE-2026-21435

JSON object : View

Products Affected

quic-go

webtransport-go

CWE

CWE-400

Uncontrolled Resource Consumption

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