CVE-2026-18547: Ultimate Member <= 2.12.1 - Authenticated (Subscriber+) Stored Cross-Site Scripting via Textarea Profile Field with HTML Support (DOM Gadget via id Attribute)
The Ultimate Member – User Profile, Registration, Login, Member Directory, Content Restriction & Membership Plugin plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Textarea Profile Field with HTML Support (DOM Gadget via id Attribute) in all versions up to, and including, 2.12.1 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with subscriber-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This is possible because the wpkses 'templates' allowlist permits the id attribute on div elements but does not neutralize unescaped quotes within its value; when pickadate.js concatenates the stored id value into an HTML string via jQuery .html() on profile page load, the smuggled onfocus and autofocus attribute syntax breaks out of attribute context and executes as JavaScript.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
wordpress/ultimate-memberto a version that resolves this vulnerability.Fixed in 2.12.1
Event History
Frequently Asked Questions
Which users can exploit this issue?
An attacker must be authenticated with at least Subscriber-level access. No additional user interaction is required from the attacker.
What profile configuration is involved?
The vulnerable path involves a textarea profile field with HTML support enabled. The payload is placed in an id attribute on a div element permitted by the templates allowlist.
When does injected code execute?
The stored script executes when a user accesses an injected profile page. On profile-page load, pickadate.js places the stored id value into an HTML string through jQuery .html(), allowing injected attributes such as onfocus and autofocus to break out of the id attribute context.
How can I determine whether an installation is in the affected range?
Check the installed Ultimate Member plugin version. The issue affects versions up to and including 2.12.1; installations using an affected version with HTML-enabled textarea profile fields are exposed to this attack path.