My Calendar Plugin up to 3.7.3 on WordPress Shortcode template cross site scripting

Summaryinfo

A vulnerability, which was classified as problematic, has been found in My Calendar Plugin up to 3.7.3 on WordPress. The impacted element is an unknown function of the component Shortcode Handler. This manipulation of the argument template causes cross site scripting. This vulnerability is registered as CVE-2026-2355. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability was found in My Calendar Plugin up to 3.7.3 on WordPress. It has been declared as problematic. Affected by this vulnerability is an unknown functionality of the component Shortcode Handler. The manipulation of the argument template with an unknown input leads to a cross site scripting vulnerability. The CWE definition for the vulnerability is CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. As an impact it is known to affect integrity. The summary by CVE is:

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.

The advisory is shared at wordfence.com. This vulnerability is known as CVE-2026-2355. The exploitation appears to be easy. The attack can be launched remotely. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1059.007 for this issue.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Type

• Calendar Software

Name

• My Calendar Plugin

Version

• 3.7.0
• 3.7.1
• 3.7.2
• 3.7.3

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