CVE-2024-56326: Jinja has a sandbox breakout through indirect reference to format method

Vulnerability summary

CVE-2024-56326 is a high (CVSS 7.8) Protection Mechanism Failure vulnerability in pallets jinja. EPSS estimates a 0.52% chance of exploitation in the next 30 days, higher than 44.3% of scored vulnerabilities.

Timeline

1. 23-12-2024
   PublishedVulnerability first disclosed.
2. 03-11-2025
   Last modifiedVulnerability information updated.

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.

• CWE-693Protection Mechanism FailureThe product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product.
• CWE-1336Improper Neutralization of Special Elements Used in a Template EngineThe product uses a template engine to insert or process externally-influenced input, but it does not neutralize or incorrectly neutralizes special elements or syntax that can be interpreted as template expressions or other code directives when processed by the engine.