, have historically been vulnerable to HTTP request smuggling Mitigation To secure an environment showing this header: Switch to a Production Server
When a web server returns the header Server: WSGIServer/0.2 CPython/3.10.4 , it reveals that the application is running on using a basic WSGI (Web Server Gateway Interface) server. In many cases, this specific version combination is associated with MkDocs 1.2.2 or older versions of Django used for local development. Key Vulnerabilities 1. Directory Traversal (CVE-2021-40978)
wsgiserver 0.2, a popular WSGI server implementation, is found to be vulnerable to a critical exploit when used with Python 3.10.4. This paper presents a detailed analysis of the vulnerability, its impact, and a proof-of-concept (PoC) exploit. We also provide recommendations for mitigation and patches to secure the server.
When a legacy, loosely written library like wsgiserver 0.2 runs on CPython 3.10.4, differences in internal behavior—specifically regarding string handling, garbage collection, and exception propagation—can be leveraged by attackers. Anatomy of the Exploit Mechanics wsgiserver 0.2 cpython 3.10.4 exploit
In the TryHackMe "Unbaked Pie" challenge, the server response was:
If wsgiserver 0.2 improperly handles malformed Transfer-Encoding or duplicate Content-Length headers, an attacker can craft a request that hides a second, nested request inside the body.
: Some webapps served by this configuration have persistent XSS vulnerabilities, where malicious scripts can be injected into database fields and executed in other users' browsers. Security Context , have historically been vulnerable to HTTP request
: Ensure you are using a patched version of Python (3.10.9 or later) and your WSGI-reliant packages (like MkDocs 1.2.3+) to resolve these known flaws. Use Production Servers : For public-facing apps, use secure alternatives like or Waitress behind a reverse proxy like Nginx. step-by-step walkthrough for a specific CTF challenge or information on patching a production environment nisdn/CVE-2021-40978 - GitHub
The server does not properly sanitize file paths, allowing attackers to request files outside the intended web root.
curl http:// :8000/%2e%2e/%2e%2e/%2e%2e/%2e%2e/etc/passwd 2. Open Redirection (CVE-2021-28861) Directory Traversal (CVE-2021-40978) wsgiserver 0
curl http:// :8000/%2e%2e/%2e%2e/%2e%2e/%2e%2e/%2e%2e/%2e%2e/%2e%2e/etc/passwd Use code with caution. Copied to clipboard Related Vulnerabilities in "thesystem" Webapp
The WSGI (Web Server Gateway Interface) server is a crucial component in the Python web ecosystem, allowing developers to run Python web applications on various web servers. However, a recently discovered vulnerability in WSGIServer 0.2, when used with CPython 3.10.4, has raised significant concerns. This blog post aims to provide an overview of the exploit, its implications, and potential mitigations.
CPython 3.10.4 is no longer the latest patch in its branch; updating to the latest 3.10.x version ensures protection against known interpreter-level vulnerabilities.
: The server does not properly sanitize URI paths, allowing an attacker to use "dot dot" sequences ( ) to reach files outside the root directory. The Impact
If the stack cannot be upgraded immediately due to legacy code dependencies, enforce strict defensive boundaries: