Subprocess Invocation Vulnerability in Fickling Package: Bypass of Safety Checks
Summary
GHSA-5cxw-w2xg-2m8h: fickling's platform module subprocess invocation evades check_safety() with LIKELY_SAFE. Affects fickling versions < 0.1.10. Fixed in 0.1.10. How to fix ↓
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Background
Fickling is a Python library designed for secure serialization and deserialization of Python objects, utilizing a safety mechanism to prevent the execution of malicious code during the loading process. However, the library has a vulnerability in its handling of the 'platform' module, which can lead to unintended subprocess invocations with attacker-controlled arguments, potentially exposing sensitive information.
Vulnerability Detail
The vulnerability arises from the 'platform' module being inadvertently excluded from the blocklist of unsafe modules in Fickling. This oversight allows crafted pickles to invoke functions like 'platform._syscmd_file', 'platform.architecture', or 'platform.libc_ver', which can execute subprocess calls with attacker-controlled arguments. The impact includes subprocess invocation that can lead to information disclosure through file type probing and arbitrary file reads, as the safety check 'check_safety()' incorrectly categorizes these invocations as 'LIKELY_SAFE'.
How To Fix
Latest published version: 0.1.12 as of 23 Oct 2026
pip install --upgrade "fickling==0.1.12"Upgrading to it may include breaking changes; the version below is the minimum fixed release for this vulnerability.
If you need the minimum change
0.1.10
This is the first release that contains the fix.
pip install --upgrade "fickling==0.1.10"Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, avoid using the 'platform' module in any pickled objects until the package is updated. Additionally, you can implement a custom safety check to filter out any pickles that may invoke the 'platform' module.
Conclusion
The Fickling package has a significant vulnerability related to subprocess invocation through the 'platform' module, which can lead to information disclosure. It is crucial to update to the patched version 0.1.10 or later to mitigate this risk. Users should also consider implementing workarounds until they can update.
See every vulnerability recorded for fickling →
FAQ
The vulnerability allows crafted pickles to bypass safety checks and invoke subprocesses with attacker-controlled arguments, leading to potential information disclosure.
You can use Vulert's playground at Vulert Scanner to check if your application is affected by this vulnerability without requiring any signup.
The CVSS score of this vulnerability is 6.9, indicating a moderate level of risk.
If you cannot update the package, avoid using the 'platform' module in your pickled objects and implement custom safety checks.
You can find more information about Fickling on its GitHub repository or its official documentation.
References
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