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CVE-2026-21435

webtransport-go CloseWithError can block indefinitely

CVSS 3.1 5.3 MEDIUMCheck source for fixed versionsKEV status unknown

Original advisory

Historical advisory recorded 23 Oct 2026 15:48:27 UTC. Read the latest advisory.

cve-program · CVE-2026-21435

Published

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.

Read the publisher's advisory

Affected versions, risk and source history

cve-program · CVE-2026-21435

Published

webtransport-go

Vendor product

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "vendor": "quic-go",
                    "product": "webtransport-go",
                    "versions": [
                        {
                            "version": "< 0.10.0",
                            "status": "affected"
                        }
                    ]
                }

Original source record · Cite this exact observation · Complete original publisher JSON