Jinja: Python code execution via str.format in Jinja (CVE-2024-56326) #shorts

Summary

In today's episode, we're delving into a newly published critical security vulnerability affecting the popular Python templating engine, Jinja. This vulnerability, identified as CVE-2024-56326, impacts applications using Jinja versions prior to 3.1.5. It allows attackers to execute arbitrary Python code, posing substantial risks to affected applications.

Product details

Jinja is an extensible templating engine commonly used in web applications to dynamically generate HTML files by embedding data in templates. The affected product versions are Jinja prior to version 3.1.5. Users utilizing these versions are advised to update to 3.1.5 immediately to mitigate potential risks.

Vulnerability type summary

The vulnerability stems from two main problems: CWE-1336, Improper Neutralization of Special Elements Used in a Template Engine, and CWE-693, Protection Mechanism Failure. These issues manifest due to an oversight in the sandboxing mechanism of the Jinja template engine, potentially allowing harmful code execution.

Details of the vulnerability

The root of CVE-2024-56326 lies in Jinja's handling of the str.format method within its sandbox environment. Attackers can exploit this by controlling template content and manipulating the application's custom filters, which might not adequately restrict executed commands. This vulnerability is crucial for environments processing untrusted templates because it could lead to arbitrary code execution. Fortunately, this has been addressed in Jinja 3.1.5, with the sandbox enhancements preventing such indirect calls.

Conclusion

To wrap up, CVE-2024-56326 is a significant discovery for both developers and security experts working with the Jinja template engine. It highlights the importance of maintaining current software versions and applying security patches promptly. Organizations using affected versions of Jinja should consider immediate updates to safeguard against potential exploitations in real-world scenarios. Stay tuned for more updates and guidance on securing your applications.

Watch the full video on YouTube: CVE-2024-56326

Remediation and exploitation details

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CVE database technical details

CVE ID

CVE-2024-56326

Description

Jinja is an extensible templating engine. Prior to 3.1.5, An oversight in how the Jinja sandboxed environment detects calls to str.format allows an attacker that controls the content of a template to execute arbitrary Python code. To exploit the vulnerability, an attacker needs to control the content of a template. Whether that is the case depends on the type of application using Jinja. This vulnerability impacts users of applications which execute untrusted templates. Jinja's sandbox does catch calls to str.format and ensures they don't escape the sandbox. However, it's possible to store a reference to a malicious string's format method, then pass that to a filter that calls it. No such filters are built-in to Jinja, but could be present through custom filters in an application. After the fix, such indirect calls are also handled by the sandbox. This vulnerability is fixed in 3.1.5.

Provider

GitHub_M

CWE / problem types

CWE-1336: Improper Neutralization of Special Elements Used in a Template Engine,CWE-693: Protection Mechanism Failure

Affected Software Versions

pallets:jinja:[{'version': '< 3.1.5', 'status': 'affected'}]

Date Published

2024-12-23T15:43:49.400Z

Last Updated

2024-12-27T17:54:33.724Z