GutenBee <= 2.20.1 - Authenticated (Author+) Arbitrary File Upload via wp_check_filetype_and_ext Filter

Summary

The GutenBee – Gutenberg Blocks plugin for WordPress is vulnerable to Arbitrary File Upload in all versions up to, and including, 2.20.1 via the gutenbee_file_and_ext_json function. This is due to a flawed strpos() substring check that only verifies whether the filename contains the string '.json' rather than confirming the filename ends with a .json extension, allowing double-extension filenames like shell.json.php to bypass validation. This makes it possible for authenticated attackers, with author-level access and above, to upload files that may be executable, which makes remote code execution possible.

Timeline

1. May 28, 2026, 6:45 AM UTCCVE published
2. May 28, 2026, 10:27 AM UTCCISA SSVC assessment

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

3. May 28, 2026, 10:35 AM UTCRecord last updated

Affected versions

• cssigniterteam GutenBee – Gutenberg Blocks

  through 2.20.1

References 9