CVE-2026-9838

MediumCVSS 6.1

Published: 10/07/2026(UTC)Updated: 10/07/2026(UTC)Translated: 11/07/2026(UTC)NVD NIST

Exploitation Probability (EPSS)

Low risk

0.30%

21th percentile - higher than 21% of all known CVEs

Summary

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. Unauthenticated attackers can inject arbitrary web scripts that execute when a user clicks a crafted link, exploiting the wp_ajax_nopriv_r34ics_ajax AJAX action without nonce verification.

Risk Assessment

An attacker can trick a user into clicking a malicious link, leading to script execution in the victim's browser session. This could result in session hijacking, account takeover, or unauthorized content modification.

Recommendation

Update the ICS Calendar plugin to the latest patched version immediately. As a temporary workaround, disable the plugin or configure a Web Application Firewall (WAF) to block requests containing the 'htmltagtitle' parameter.

Other vulnerabilities in ICS Calendar

CVE-2026-59516High
The ICS Calendar WordPress plugin up to version 12.1.1 contains a reflected Cross-site Scripting (XSS) vulnerability due to improper input neutralization during page generation. An attacker can inject malicious JavaScript via a crafted HTTP request.

Original NVD description (English source)

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.