CVE-2026-42544

Granian: Unauthenticated DoS via WebSocket subprotocol header panic

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.

Affected

emmett-framework · granian

CVSS v3.1 GITHUB

7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

0.46% chance of exploitation in the next 30 days, 39th percentile

Published

2026-05-12

Updated

2026-05-18

Proof-of-concept exploits (1)

• advisories/GHSA-vrg7-482j-p6f6

References

• CVE Record
• NVD entry