Package Instance

Jinja2 vulnerable to sandbox breakout through attr filter selecting format method
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.

Jinja has a sandbox breakout through indirect reference to format method
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.

Jinja vulnerable to HTML attribute injection when passing user input as keys to xmlattr filter
The `xmlattr` filter in affected versions of Jinja accepts keys containing non-attribute characters. XML/HTML attributes cannot contain spaces, `/`, `>`, or `=`, as each would then be interpreted as starting a separate attribute. If an application accepts keys (as opposed to only values) as user input, and renders these in pages that other users see as well, an attacker could use this to inject other attributes and perform XSS. The fix for the previous GHSA-h5c8-rqwp-cp95 CVE-2024-22195 only addressed spaces but not other characters.

Accepting keys as user input is now explicitly considered an unintended use case of the `xmlattr` filter, and code that does so without otherwise validating the input should be flagged as insecure, regardless of Jinja version. Accepting _values_ as user input continues to be safe.

Jinja vulnerable to HTML attribute injection when passing user input as keys to xmlattr filter
The `xmlattr` filter in affected versions of Jinja accepts keys containing spaces. XML/HTML attributes cannot contain spaces, as each would then be interpreted as a separate attribute. If an application accepts keys (as opposed to only values) as user input, and renders these in pages that other users see as well, an attacker could use this to inject other attributes and perform XSS. Note that accepting keys as user input is not common or a particularly intended use case of the `xmlattr` filter, and an application doing so should already be verifying what keys are provided regardless of this fix.