{"id":"CVE-2026-42544","aliases":["GHSA-vrg7-482j-p6f6","PYSEC-2026-2503"],"url":"https://o3.security/vulnerability/CVE-2026-42544","summary":"Granian: Unauthenticated DoS via WebSocket subprotocol header panic","details":"Granian is a Rust HTTP server for Python applications. From 1.2.0 to 2.7.4, Granian aborts a worker process when an unauthenticated client sends a WebSocket upgrade request whose Sec-WebSocket-Protocol header contains non-ASCII bytes. The crash happens in Granian's WebSocket scope construction path, before the ASGI application is invoked. This vulnerability is fixed in 2.7.4.","published":"2026-05-12T21:46:19.734Z","modified":"2026-08-07T11:31:19.353735070Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"granian","fixedVersion":"2.7.4"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42544.json"},{"type":"ADVISORY","url":"https://github.com/emmett-framework/granian/security/advisories/GHSA-vrg7-482j-p6f6"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-42544"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-07T11:31:19.353735070Z"}}