CVE-2025-50182: 
Python vulnerability analysis and mitigation

CVE-2025-50182 affects urllib3, a user-friendly HTTP client library for Python, in versions 2.2.0 to 2.5.0. The vulnerability was discovered and disclosed on June 18, 2025, specifically impacting systems utilizing urllib3 with Pyodide runtime that leverages JavaScript Fetch API or XMLHttpRequest. The core issue relates to the library's inability to control redirects in browsers and Node.js environments when used in a Pyodide runtime (GitHub Advisory, NVD).

The vulnerability stems from urllib3's implementation when used in a Pyodide runtime environment. While urllib3 provides mechanisms to control redirects through retries and redirect parameters, these controls are ignored in Pyodide environments where the runtime itself determines redirect behavior. The issue has been assigned a CVSS v3.1 base score of 5.3 (Medium) with the vector string CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N, indicating network attack vector with high complexity, requiring low privileges but no user interaction (GitHub Advisory, Wiz).

The vulnerability primarily affects applications attempting to mitigate SSRF (Server-Side Request Forgery) or open redirect vulnerabilities by disabling redirects. When using urllib3 in a Pyodide runtime, these security controls may be bypassed as the runtime's redirect mechanism takes precedence, potentially leaving applications vulnerable to SSRF attacks (GitHub Advisory).

For Node.js environments, upgrading to urllib3 version 2.5.0 or later is recommended as it includes a patch for this vulnerability. For browser environments, no direct workaround is available as browsers provide no suitable mechanism for urllib3 to control redirects - XMLHttpRequest provides no control over redirects, and the Fetch API returns opaqueredirect responses lacking data when redirects are controlled manually (GitHub Advisory, Ubuntu Notice).