https://cve.radiocsirt.org/rss/recent/all/10 Most recent entries from all 2026-10-07T13:42:49.938452+00:00 Vulnerability-Lookup csirt@opendfir.org python-feedgen Contains only the most 10 recent entries. https://cve.radiocsirt.org/vuln/euvd-2026-268699 EUVD-2026-268699 2026-10-07T13:42:49.986896+00:00 EUVD-2026-268699 https://cve.radiocsirt.org/vuln/fkie_cve-2026-21435 fkie_cve-2026-21435 2026-10-07T13:42:49.986933+00:00

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.

 https://cve.radiocsirt.org/vuln/ghsa-px4r-g4p3-hhqv GHSA-px4r-g4p3-hhqv — webtransport-go: CloseWithError can block indefinitely 2026-10-07T13:42:49.986967+00:00

Affected: Go: github.com/quic-go/webtransport-go

## Summary 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.

## Details WebTransport over HTTP/3 signals session termination by sending a WT_CLOSE_SESSION capsule on the CONNECT stream. The capsule is only needed to transmit a reason phrase and an error code to the peer. After the capsule is sent, the CONNECT stream is closed. In affected versions, the closure procedure blocked indefinitely while waiting for sufficient QUIC flow control credit from the peer. A malicious peer can withhold this credit, preventing the capsule from being sent.

## The Fix webtransport-go now attempts to send the WT_CLOSE_SESSION capsule with a short deadline. If the capsule cannot be sent within this deadline, the CONNECT stream is reset instead. This closes the WebTransport session promptly without transmitting the optional error details. This prevents indefinite blocking on session closure.