CVE-2026-22612: Fickling Vulnerable to Detection Bypass Due to Builtins Blindness
Summary
CVE-2026-22612: Fickling vulnerable to detection bypass due to "builtins" blindness. Affects fickling versions < 0.1.7. Fixed in 0.1.7. How to fix ↓
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Background
Fickling is a Python package designed for security analysis of Pickle bytecode by converting it into Abstract Syntax Tree (AST) nodes. It aims to identify unsafe imports and potential security risks within serialized data. However, it has a critical vulnerability that allows certain dangerous built-in functions to bypass detection, compromising its security analysis capabilities.
Vulnerability Detail
The vulnerability arises from Fickling's failure to emit AST nodes for built-in imports during its analysis process. Specifically, when converting Pickle bytecode to AST, imports from builtins such as 'import' are omitted, rendering the security scanner blind to potentially dangerous operations. This oversight can lead to security bypasses, allowing malicious payloads to execute arbitrary code without being flagged by the scanner. For instance, an attacker can create a payload that uses the built-in 'import' function to import the 'os' module and execute system commands, all while evading detection.
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
0.1.7
This is the first release that contains the fix.
pip install --upgrade "fickling==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 can manually inspect and analyze Pickle files for unsafe imports, particularly those involving built-ins. However, this is not a foolproof solution and should only be considered until the package is updated.
Conclusion
The Fickling package has a significant vulnerability that allows for detection bypass of dangerous built-in imports, posing a risk of arbitrary code execution. Users are strongly advised to update to the latest version to secure their applications. Additionally, utilizing tools like Vulert can help monitor and alert for such vulnerabilities in real-time.
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FAQ
The vulnerability has a CVSS score of 8.9, indicating a high severity level.
You can use Vulert's playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
Exploitation of this vulnerability can lead to arbitrary code execution, allowing attackers to run malicious commands on the host system.
Yes, a patch is available in version 0.1.7 of Fickling. Users should upgrade to this version to mitigate the risk.
If immediate updates are not possible, consider reviewing and sanitizing any Pickle files for unsafe imports as a temporary measure.
References
Related vulnerabilities
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