room34 ICS Calendar Plugin up to 12.0.9 on WordPress Shortcode htmltagtitle cross site scripting

Summaryinfo

A vulnerability, which was classified as problematic, was found in room34 ICS Calendar Plugin up to 12.0.9. This affects an unknown part of the component Shortcode Handler. Such manipulation of the argument htmltagtitle leads to cross site scripting. This vulnerability is documented as CVE-2026-9838. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in room34 ICS Calendar Plugin up to 12.0.9 and classified as problematic. Affected by this issue is some unknown functionality of the component Shortcode Handler. The manipulation of the argument htmltagtitle with an unknown input leads to a cross site scripting vulnerability. Using CWE to declare the problem leads to 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. Impacted is integrity. CVE summarizes:

The ICS Calendar plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via the 'htmltagtitle' parameter in all versions up to, and including, 12.0.9 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that execute if they can successfully trick a user into performing an action such as clicking on a link. The vulnerability is reachable via the unauthenticated wp_ajax_nopriv_r34ics_ajax AJAX action, which accepts attacker-controlled js_args values merged over stored shortcode configuration without nonce verification, allowing the htmltagtitle key to bypass the normal shortcode allowlist check.

The advisory is shared for download at wordfence.com. This vulnerability is handled as CVE-2026-9838 since 05/28/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1059.007.

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

• WordPress Plugin

Vendor

• room34

Name

• ICS Calendar Plugin

Version

• 12.0.0
• 12.0.1
• 12.0.2
• 12.0.3
• 12.0.4
• 12.0.5
• 12.0.6
• 12.0.7
• 12.0.8
• 12.0.9

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

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