Critical Security Vulnerability in python-jinja2: Jinja Sandbox Breakout
Summary
RLSA-2025:3388: Important: python-jinja2 security update. Affects python-jinja2 versions < 0:2.10.1-7.el8_10. Fixed in 0:2.10.1-7.el8_10. How to fix ↓
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Background
python-jinja2 is a popular templating engine for Python, widely used for rendering dynamic web pages. It allows developers to create templates that can be populated with data, making it essential for web applications. The package supports features like template inheritance, macros, and automatic escaping, enhancing both functionality and security. However, it is susceptible to vulnerabilities that can compromise the integrity of applications using it.
Vulnerability Detail
The vulnerability identified as CVE-2025-27516 involves a sandbox breakout in Jinja, specifically through the 'attr' filter selecting the 'format' method. This flaw allows an attacker to execute arbitrary code outside the intended sandbox environment, potentially leading to unauthorized access and manipulation of sensitive data. The CVSS score for this vulnerability is 7.3, indicating a high severity level that necessitates immediate attention.
How To Fix
Minimum fixed version
0:2.10.1-7.el8_10
This is the first release that contains the fix.
sudo dnf update python-jinja2Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary measure, you can limit the use of the 'attr' filter in your templates until the package is updated. This can help mitigate the risk of exploitation while you prepare for the update.
Conclusion
The python-jinja2 package has a critical vulnerability (CVE-2025-27516) that allows for sandbox breakout, posing significant risks to applications. It is crucial to update to the patched version to mitigate these risks. Utilizing tools like Vulert can further enhance your security posture by monitoring for vulnerabilities in real-time.
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FAQ
CVE-2025-27516 is a security vulnerability in the python-jinja2 package that allows for sandbox breakout through the 'attr' filter, enabling potential code execution outside the intended environment.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
Failing to address this vulnerability could lead to unauthorized access to sensitive data, code execution, and potential compromise of your application and its users.
Yes, a patch is available in version 0:2.10.1-7.el8_10 of the python-jinja2 package. Updating to this version will resolve the vulnerability.
Vulert is a tool that monitors and alerts for open-source vulnerabilities in software using just a manifest file like package-lock.json. It helps developers stay informed about vulnerabilities in their applications.
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