CVE-2026-42544
Granian: Unauthenticated DoS via WebSocket subprotocol header panic
CVSS Score
7.5
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-20 CWE-248 CWE-400 |
| Vendor | emmett-framework |
| Product | granian |
| Published | May 12, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Affected Versions
emmett-framework / granian
>= 1.2.0, < 2.7.4