The Same Category Posts plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the widget title placeholder functionality in all versions up to, and including, 1.1.19. This is due to the use of `htmlspecialchars_decode()` on taxonomy term names before output, which decodes HTML entities that WordPress intentionally encodes for safety. This makes it possible for authenticated attackers, with Author-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.