CVE-2026-33139: PySpector Plugin Sandbox Bypass Leading to Arbitrary Code Execution
Summary
CVE-2026-33139: PySpector has a Plugin Sandbox Bypass leads to Arbitrary Code Execution. Affects pyspector versions < 0.1.7. Fixed in 0.1.7. How to fix ↓
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Background
PySpector is a Python package designed to facilitate the analysis and validation of plugins within Python applications. It allows users to install third-party plugins to extend functionality while ensuring security through a validation process. However, versions up to 0.1.6 are vulnerable to a security flaw that undermines this validation, exposing users to potential risks.
Vulnerability Detail
The vulnerability arises from a bypass in the plugin validation mechanism of PySpector. The function 'validate_plugin_code()' is intended to perform static AST analysis to block dangerous API calls. However, it fails to handle indirect function calls made via 'getattr()', which allows malicious plugins to bypass security checks. This flaw can lead to arbitrary code execution on the user's machine, enabling attackers to gain full access to the filesystem, exfiltrate sensitive data, and establish persistence mechanisms.
How To Fix
Minimum fixed version
0.1.7
This is the first release that contains the fix.
pip install --upgrade "pyspector==0.1.7"Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, users should avoid installing third-party plugins from untrusted sources until they can update to the patched version. Additionally, users can manually inspect plugin code for suspicious patterns, particularly those using 'getattr()' for function calls.
Conclusion
The vulnerability identified as CVE-2026-33139 in PySpector poses significant risks due to a bypass in the plugin validation process. Users are strongly encouraged to update to version 0.1.7 or later to mitigate these risks and ensure the security of their applications.
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FAQ
The CVSS score of this vulnerability is 8.3, indicating a high severity level.
You can use Vulert's playground at Vulert Scanner to check if your application is affected without requiring any signup.
If you cannot update immediately, refrain from installing untrusted third-party plugins and manually review any existing plugins for security risks.
Exploitation can lead to arbitrary code execution, allowing attackers to access sensitive data, manipulate files, and potentially compromise entire systems.
Yes, using Vulert, you can monitor and receive alerts for open-source vulnerabilities in your software by simply using the Pipfile.lock.
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