CVE-2026-21435

EUVD-2026-6717
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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
5.3 MEDIUM
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
GitHub_MCNA
5.3 MEDIUM
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Base Score
CVSS 3.x
EPSS Score
Percentile: 3%
Affected Products (NVD)
VendorProductVersion
quic-gowebtransport-go
𝑥
< 0.10.0
𝑥
= Vulnerable software versions
Common Weakness Enumeration
References
https://github.com/quic-go/webtransport-go/releases/tag/v0.10.0
https://github.com/quic-go/webtransport-go/security/advisories/GHSA-px4r-g4p3-hhqv