Stored XSS in PySpector HTML Report Generation leads to Javascript Code Execution
Date: 2026-03
Affected: pip/pyspector
Attack vector: xss
Category: vulnerability-disclosure
Severity: Medium
CVE: CVE-2026-33140
CWE: CWE-79

### 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-a9


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