Improper Neutralization of Special Elements Used in a Template Engine Affecting jinja2 package, versions <2.10-1ubuntu0.18.04.1+esm4


Severity

Recommended
medium

Based on Ubuntu security rating.

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  • Snyk IDSNYK-UBUNTU1804-JINJA2-9298759
  • published11 Mar 2025
  • disclosed5 Mar 2025

Introduced: 5 Mar 2025

NewCVE-2025-27516  (opens in a new tab)
CWE-1336  (opens in a new tab)

How to fix?

Upgrade Ubuntu:18.04 jinja2 to version 2.10-1ubuntu0.18.04.1+esm4 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream jinja2 package and not the jinja2 package as distributed by Ubuntu. See How to fix? for Ubuntu:18.04 relevant fixed versions and status.

Jinja is an extensible templating engine. Prior to 3.1.6, an oversight in how the Jinja sandboxed environment interacts with the |attr filter 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 use the |attr filter to get a reference to a string's plain format method, bypassing the sandbox. After the fix, the |attr filter no longer bypasses the environment's attribute lookup. This vulnerability is fixed in 3.1.6.

CVSS Base Scores

version 3.1