Vulnerability record · CVE-2026-21435 · published 12 February 2026

CVE-2026-21435: Quic-go webtransport-go uncontrolled resource consumption vulnerability

Quic Go · Webtransport Go

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.

7.5 CVSS 3.1 High EPSS 0.43% · top 65.4% CWE-400 · Uncontrolled resource consumption

7.5CVSS 3.1 base score

0.43%EPSS exploitation probability, 30 days

NoNot in CISA KEV

1Affected product versions listed by NVD

2References

17 Jun 2026Last modified by NVD

Description

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

Webtransport Go Quic Go

References

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

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-21435), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.