Vulnerability · Published May 12, 2026 · Assigned by GitHub_M
CVE-2026-42544Granian: Unauthenticated DoS via WebSocket subprotocol header panic
High 7.5
In plain English
A high-severity improper input validation in granian from emmett-framework. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 33% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| PyPI | granian | 2.7.4 | GHSA-vrg7-482j-p6f6 |
| PyPI | granian | 2.7.4 | PYSEC-2026-2503 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| emmett-framework | granian | >= 1.2.0, < 2.7.4 |
Weakness: CWE-20, CWE-248, CWE-400 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H