Remote Code Execution Risk in Flask-Caching Package Due to Pickle Serialization Flaw
Summary
DEBIAN-CVE-2021-33026: The Flask-Caching extension through 1.10.1 for Flask relies on Pickle for serialization, which may lead to remote code execution or local privilege escalation. Affects flask-caching versions 1.10.1-1 – 2.3.1-1. No fix is published. How to fix ↓
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Background
Flask-Caching is an extension for Flask that provides caching capabilities to enhance the performance of web applications. It supports various backends such as filesystem, Memcached, and Redis. The package is widely used in Python web development to optimize response times by storing frequently accessed data. However, a critical vulnerability has been identified in versions up to 1.10.1, where the reliance on Pickle for serialization poses significant security risks.
Vulnerability Detail
The vulnerability arises from the use of Pickle for serialization in Flask-Caching, which can lead to remote code execution or local privilege escalation. If an attacker gains access to the cache storage (e.g., filesystem, Memcached, Redis), they can craft a malicious payload, poison the cache, and execute arbitrary Python code. Although exploitation is deemed unlikely unless the machine is already compromised, it remains a serious concern as it could allow unauthorized access and control over the affected system.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
As a temporary workaround, consider disabling caching or using a different serialization method that does not rely on Pickle. This can help mitigate the risk until the package is updated. Additionally, ensure that access to cache storage is restricted to trusted users only.
Conclusion
The vulnerability in Flask-Caching due to the use of Pickle for serialization poses significant security risks, including remote code execution. It is crucial for users to update to a patched version and consider workarounds to secure their applications. Regular monitoring for vulnerabilities using tools like Vulert can help maintain application security.
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FAQ
Flask-Caching is an extension for Flask that provides caching mechanisms to improve the performance of web applications.
The vulnerability involves the use of Pickle for serialization, which can be exploited to execute arbitrary code if an attacker gains access to the cache.
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 could lead to remote code execution or local privilege escalation, allowing attackers to gain unauthorized access to the system.
Yes, a patched version of Flask-Caching is available. It is recommended to update to a version greater than 1.10.1 to mitigate the risk.
References
Related vulnerabilities
Recent vulnerabilities recorded for flask-caching.
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