Same Category Posts WordPress Plugin Stored Cross-Site Scripting Vulnerability

A stored cross-site scripting vulnerability has been identified in the Same Category Posts plugin for WordPress, affecting all versions through 1.1.19. The issue arises from the widget title placeholder functionality, where taxonomy term names are output using 'htmlspecialchars_decode()'. This decoding process removes HTML entity encoding that WordPress applies for security, allowing authenticated attackers with Author-level access or higher to inject arbitrary scripts. These scripts are executed when users access the affected page.

Impact

Exploitation of this vulnerability allows for stored cross-site scripting, where injected scripts are executed in the context of the user viewing the page.

Reproduction

To reproduce this vulnerability, an authenticated user with Author-level access or higher can inject scripts through the widget title placeholder. The injected scripts will be executed when the widget is displayed on a page.

Remediation

Users are advised to update the Same Category Posts plugin to version 1.1.20 or later, where this vulnerability has been patched.