{"id":"CVE-2026-21435","summary":"webtransport-go CloseWithError can block indefinitely","details":"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.","aliases":["GHSA-px4r-g4p3-hhqv","GO-2026-4488"],"modified":"2026-05-18T05:58:31.628635533Z","published":"2026-02-12T18:22:58.098Z","related":["CGA-cj6m-9rxm-v36r","SUSE-SU-2026:0757-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/21xxx/CVE-2026-21435.json","cwe_ids":["CWE-400"],"cna_assigner":"GitHub_M"},"references":[{"type":"WEB","url":"https://github.com/quic-go/webtransport-go/releases/tag/v0.10.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/21xxx/CVE-2026-21435.json"},{"type":"ADVISORY","url":"https://github.com/quic-go/webtransport-go/security/advisories/GHSA-px4r-g4p3-hhqv"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-21435"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/quic-go/webtransport-go","events":[{"introduced":"0"},{"fixed":"9d448b125754f4c83064afb2c586221214e55eec"}]}],"versions":["v0.9.0","v0.8.0","v0.7.0","v0.6.0","v0.5.3","v0.5.2","v0.5.1","v0.5.0","v0.4.3","v0.4.2","v0.4.1","v0.4.0","v0.3.0","v0.2.0","v0.1.0"],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-21435.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"}]}