The Gallery Block (Meow Gallery) plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the ‘data_atts’ parameter in versions up to, and including, 5.1.3 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with contributor-level permissions and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
CWE-79