Arbitrary Code Injection Affecting pyinstaller package, versions [,6.0.0)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Start learning- Snyk IDSNYK-PYTHON-PYINSTALLER-12579198
- published10 Sept 2025
- disclosed9 Sept 2025
- creditUnknown
Introduced: 9 Sep 2025
NewCVE-2025-59042 (opens in a new tab)How to fix?
Upgrade pyinstaller to version 6.0.0 or higher.
Overview
pyinstaller is a package that bundles a Python application and all its dependencies into a single package
Affected versions of this package are vulnerable to Arbitrary Code Injection in the bootstrap process. An attacker can achieve arbitrary code execution by placing malicious files or directories in the same location as a vulnerable PyInstaller application. When the application starts, it can be tricked into loading and running the attacker's Python code due to how PyInstaller handles sys.path and attempts to load an optional bytecode decryption module. If the application runs with elevated privileges, this can lead to local privilege escalation. This exploit works in both "onedir" and "onefile" modes, but only if the optional bytecode encryption feature was not enabled during the application's build.
Notes: This is only exploitable if the filesystem supports creation of files/directories that contain '?' in their name (i.e., non-Windows systems) and the attacker is able to determine the offset at which the PYZ archive is embedded in the executable.
Workaround
This vulnerability can be mitigated by ensuring proper permissions on directories containing security-sensitive executables (for example, executables with the setuid bit set).