Stored XSS in PySpector HTML Report Generation leads to Javascript Code Execution

Summary

PySpector versions <= 0.1.6 are affected by a stored Cross-Site Scripting (XSS) vulnerability in the HTML report generator. When PySpector scans a Python file containing JavaScript payloads (i.e. inside a string passed to eval() ), the flagged code snippet is interpolated into the HTML report without sanitization. Opening the generated report in a browser causes the embedded JavaScript to execute in the browser's local file context.

Impact

An attacker can craft a malicious Python file (for example, hosted in a public repository), designed to be scanned by PySpector. When a victim scans this file and opens the resulting HTML report, arbitrary JavaScript executes in their browser. While the file:// context limits the attacker's ability to exfiltrate cookies or make credentialed requests, the following is still achievable:

• Arbitrary DOM manipulation
• Redirects to attacker-controlled pages
• Theft of locally accessible data via fetch() or XMLHttpRequest to file:// paths (browser-dependent)

Any user of PySpector who scans untrusted code and generates HTML reports, is potentially affected.

PoC

The following steps reproduce the vulnerability on PySpector <= 0.1.6:

1. Create a malicious Python file containing a JavaScript payload embedded in a string argument to eval(), and run PySpector against the file, generating an HTML report: <img width="871" height="752" alt="image" src="https://github.com/user-attachments/assets/1b0a57f2-3632-4347-a9b7-6a94dc2e82b2" />
2. Open the generated HTML report in any browser: <img width="1920" height="920" alt="image" src="https://github.com/user-attachments/assets/a4075c4a-6153-41b4-ad77-81d009d7a9f8" />