CVE-2026-42544CWE-20CWE-248CWE-400

Granian: Unauthenticated DoS via WebSocket subprotocol header panic

High · published May 12, 2026

CVSS v3.1
7.5
EPSS
0%
Percentile
38.9
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
7.5 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS v4.0
Not supplied
EPSS
0.00460 · 38.9th percentile
Weaknesses
CWE-20 · Improper Input Validation; CWE-248 · Uncaught Exception; CWE-400 · Uncontrolled Resource Consumption
Published
2026-05-12T21:46Z
EPSS history
Timeline
  • 12 MAY 21:46Z
    Granian: Unauthenticated DoS via WebSocket subprotocol header panic
    cvelistv5