What the vulnerability does
01Description
The My Calendar – Accessible Event Manager plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the `template` attribute of the `[my_calendar_upcoming]` shortcode in all versions up to, and including, 3.7.3. This is due to the use of `stripcslashes()` on user-supplied shortcode attribute values in the `mc_draw_template()` function, which decodes C-style hex escape sequences (e.g., `\x3c` to `<`) at render time, bypassing WordPress's `wp_kses_post()` content sanitization that runs at save time. 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.
Explanation of Vulnerability in Simple Terms
02Summary
My Calendar versions up to 3.7.3 contain a cross-site scripting (XSS) vulnerability that allows authenticated users to inject malicious scripts affecting other users. The vulnerability has scope impact, meaning injected code can affect users beyond the immediate component. Site administrators should update to a version newer than 3.7.3 to remediate this issue.
What an attacker can do
03Attacker Capabilities
Inject malicious scripts that execute in other users' browsers when they view affected pages.
Potential impact on your site
04Site Impact
Authenticated users can inject code affecting other site visitors, potentially compromising user sessions or stealing data.
Conditions required to exploit
05Prerequisites
Attacker must have a low-privilege account (e.g., contributor or subscriber role) on the site.
Key dates
06Disclosure timeline
March 4, 2026
CVE published
April 8, 2026
Record updated
