CVE-2014-1402: Incorrect Privilege Assignment in Jinja2

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Background

Jinja2 is a popular templating engine for Python. It provides a way to generate dynamic content by combining templates with data. Jinja2 is widely used in web development frameworks and other applications that require dynamic content generation. However, a vulnerability has been discovered in Jinja2 versions prior to 2.7.2 that allows local users to gain privileges through a specific file manipulation technique.

Vulnerability Detail

The vulnerability in Jinja2 arises from the default configuration of bccache.FileSystemBytecodeCache. This component is responsible for caching compiled templates to improve performance. However, it fails to properly create temporary files, which can be exploited by local users. An attacker can craft a malicious .cache file with a name starting with '_jinja2' in the /tmp directory. When Jinja2 attempts to load this file, it inadvertently grants the attacker elevated privileges. This privilege escalation can lead to unauthorized access, data manipulation, or other malicious activities.

pip install --upgrade "jinja2==3.1.6"

pip install --upgrade "jinja2==2.7.2"

Workaround

If upgrading to the latest version of Jinja2 is not immediately feasible, a temporary workaround can be implemented. The workaround involves modifying the default configuration of bccache.FileSystemBytecodeCache to use a different directory for temporary files. By specifying a secure directory with restricted access, the risk of privilege escalation can be mitigated. Here is an example of how to modify the configuration:

import jinja2

jinja2.defaults.DEFAULT_CACHE_SIZE = 0
jinja2.Environment(bytecode_cache=jinja2.FileSystemBytecodeCache('/secure/temp/dir'))

This code snippet sets the cache size to 0 to disable caching and specifies a secure directory ('/secure/temp/dir') for temporary files.

Conclusion

In conclusion, the vulnerability in Jinja2 (CVE-2014-1402) allows local users to gain elevated privileges through a specific file manipulation technique. To mitigate this vulnerability, it is recommended to upgrade to Jinja2 version 2.7.2 or later. If immediate upgrade is not feasible, a temporary workaround can be implemented by modifying the configuration. For further assistance and support in vulnerability remediation, please contact DevNack.com.

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