Jinja vulnerable to HTML attribute injection when passing user input as keys to xmlattr filter

Summary

Jinja is an extensible templating engine. 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 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. This vulnerability is fixed in 3.1.4.

Timeline

1. May 6, 2024, 2:41 PM UTCCVE published
2. May 9, 2024, 5:53 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. Nov 3, 2025, 9:54 PM UTCRecord last updated

Affected versions

• pallets jinja

  fixed in 3.1.4

• jinja2PyPI

  fixed in 3.1.4

References 13