CVE-2026-42544

HIGH LAB

Granian: Unauthenticated DoS via WebSocket subprotocol header panic

Title source: cna
STIX 2.1

Exploitation Summary

EIP tracks 1 public exploit for CVE-2026-42544. PoCs published by dwisiswant0.

AI-analyzed exploit summary This repository contains a functional exploit for CVE-2026-42544, a denial-of-service vulnerability in Granian ASGI/WSGI server. The exploit sends a crafted WebSocket upgrade request with non-ASCII bytes in the Sec-WebSocket-Protocol header, causing the server to panic and abort.

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.

Exploits (1)

github WORKING POC 1 stars
by dwisiswant0 · pythonpoc
https://github.com/dwisiswant0/neo-pocs/tree/master/2026/CVE-2026-42544

This repository contains a functional exploit for CVE-2026-42544, a denial-of-service vulnerability in Granian ASGI/WSGI server. The exploit sends a crafted WebSocket upgrade request with non-ASCII bytes in the Sec-WebSocket-Protocol header, causing the server to panic and abort.

Classification
Working Poc 100%
Attack Type
Dos
Complexity
Trivial
Reliability
Reliable
Target: Granian (>= 1.2.0, < 2.7.4)
No auth needed
Prerequisites: Network access to the target Granian server
devstral-2 · analyzed May 14, 2026 Full analysis →

References (1)

Core 1
Core References

Scores

CVSS v3 7.5
EPSS 0.0008
EPSS Percentile 24.2%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CISA SSVC

Vulnrichment
Exploitation poc
Automatable yes
Technical Impact partial

Lab Environment

COMMUNITY
Community Lab

Details

CWE
CWE-20 CWE-248 CWE-400
Status published
Products (2)
emmett-framework/granian >= 1.2.0, < 2.7.4
pypi/granian 1.2.0 - 2.7.4PyPI
Published May 12, 2026
Tracked Since May 13, 2026