CVE-2026-42544: CWE-20: Improper Input Validation in emmett-framework granian
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.
AI Analysis
Technical Summary
Granian versions >= 1.2.0 and < 2.7.4 improperly validate input in the WebSocket upgrade request path. Specifically, if the Sec-WebSocket-Protocol header contains non-ASCII bytes, the server aborts a worker process, leading to a denial-of-service condition. This occurs before the ASGI application is called, indicating the issue lies in the server's WebSocket scope construction logic. The vulnerability is classified under CWE-20 (Improper Input Validation), CWE-248 (Uncaught Exception), and CWE-400 (Uncontrolled Resource Consumption). The flaw is resolved in Granian version 2.7.4.
Potential Impact
An unauthenticated attacker can cause a denial-of-service by sending a crafted WebSocket upgrade request with non-ASCII bytes in the Sec-WebSocket-Protocol header, crashing a worker process. This impacts availability but does not affect confidentiality or integrity. There are no known exploits in the wild as of the published date.
Mitigation Recommendations
This vulnerability is fixed in Granian version 2.7.4. Users should upgrade to version 2.7.4 or later to remediate this issue. Patch status is not explicitly stated beyond the fixed version, so verify with the vendor advisory for the latest remediation guidance.
CVE-2026-42544: CWE-20: Improper Input Validation in emmett-framework granian
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.
CVSS v3.1
Score 7.5high
Affected software
pkg:cargo/github/emmett-framework/granianRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Granian versions >= 1.2.0 and < 2.7.4 improperly validate input in the WebSocket upgrade request path. Specifically, if the Sec-WebSocket-Protocol header contains non-ASCII bytes, the server aborts a worker process, leading to a denial-of-service condition. This occurs before the ASGI application is called, indicating the issue lies in the server's WebSocket scope construction logic. The vulnerability is classified under CWE-20 (Improper Input Validation), CWE-248 (Uncaught Exception), and CWE-400 (Uncontrolled Resource Consumption). The flaw is resolved in Granian version 2.7.4.
Potential Impact
An unauthenticated attacker can cause a denial-of-service by sending a crafted WebSocket upgrade request with non-ASCII bytes in the Sec-WebSocket-Protocol header, crashing a worker process. This impacts availability but does not affect confidentiality or integrity. There are no known exploits in the wild as of the published date.
Mitigation Recommendations
This vulnerability is fixed in Granian version 2.7.4. Users should upgrade to version 2.7.4 or later to remediate this issue. Patch status is not explicitly stated beyond the fixed version, so verify with the vendor advisory for the latest remediation guidance.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-04-28T16:56:50.191Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a03a7e4cbff5d86101ff96d
Added to database: 05/12/2026, 22:21:24 UTC
Last enriched: 05/20/2026, 18:24:36 UTC
Last updated: 07/31/2026, 19:22:58 UTC
Views: 80
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