What the vulnerability does
01Description
The Calendar plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'event_desc' parameter in all versions up to, and including, 1.3.16 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with Contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page, granted they can convince an administrator to enable lower privilege users to manage calendar events via the plugin settings.
Explanation of Vulnerability in Simple Terms
02Summary
Calendar versions 1.3.16 and earlier contain a cross-site scripting vulnerability that allows authenticated users to inject malicious scripts. The vulnerability affects the scope beyond the vulnerable component, potentially impacting other users or site functionality. Upgrade to version 1.3.17 or later to remediate.
What an attacker can do
03Attacker Capabilities
Inject malicious scripts that execute in other users' browsers or affect site functionality.
Potential impact on your site
04Site Impact
Authenticated users can inject scripts affecting other users or site behavior; data theft or account compromise possible.
Conditions required to exploit
05Prerequisites
Attacker must be authenticated with low-level privileges; no user interaction required.
Key dates
06Disclosure timeline
December 23, 2025
CVE published
April 8, 2026
Record updated
