Summary
Stored XSS in PySpector HTML Report Generation leads to Javascript Code Execution
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.
PoC
The following steps reproduce the vulnerability on PySpector <= 0.1.6:
- 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:
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()orXMLHttpRequesttofile://paths (browser-dependent)
Any user of PySpector who scans untrusted code and generates HTML reports, is potentially affected.
Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2026-33140? CVE-2026-33140 is a medium-severity cross-site scripting (XSS) vulnerability in pyspector (pip), affecting versions <= 0.1.6. It is fixed in 0.1.7. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
- Which versions of pyspector are affected by CVE-2026-33140? pyspector (pip) versions <= 0.1.6 is affected.
- Is there a fix for CVE-2026-33140? Yes. CVE-2026-33140 is fixed in 0.1.7. Upgrade to this version or later.
- Is CVE-2026-33140 exploitable, and should I be worried? Whether CVE-2026-33140 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-33140 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-33140? Upgrade
pyspectorto 0.1.7 or later.