Vulnerability · Published Jul 10, 2026 · Assigned by Wordfence

CVE-2026-9838ICS Calendar <= 12.0.9 - Reflected Cross-Site Scripting via 'htmltagtitle' Parameter

Medium 6.1

In plain English

A medium-severity cross-site scripting in ICS Calendar from room34. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 43% of all known vulnerabilities).

Severity (CVSS 3.1)6.1Medium

Exploit odds (30 days)0.5%top 57.4% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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.

Affected products (as reported)

Vendor	Product	Versions
room34	ICS Calendar	0 – through 12.0.9

Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

In plain English

Official description

Affected products (as reported)

References