CVE-2026-3551 Cross-site scripting in Custom New User Notification
Administrators can inject scripts via plugin settings, potentially targeting super admins in multi-site installations.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-3551?
CVE-2026-3551 is a medium-severity cross-site scripting vulnerability in rafasashi Custom New User Notification, published on 16 Apr 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Official description
The Custom New User Notification plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin's admin settings in all versions up to, and including, 1.2.0. This is due to insufficient input sanitization and output escaping on multiple settings fields including 'User Mail Subject', 'User From Name', 'User From Email', 'Admin Mail Subject', 'Admin From Name', and 'Admin From Email'. The settings are registered via register_setting() without sanitize callbacks, and the values retrieved via get_option() are echoed directly into HTML input value attributes without esc_attr(). This makes it possible for authenticated attackers, with Administrator-level access and above, to inject arbitrary web scripts in the plugin settings page that will execute whenever a user accesses that page. This could be used in multi-site installations where administrators of subsites could target super administrators.
Weakness: CWE-79
Which versions are affected by CVE-2026-3551?
How do I fix CVE-2026-3551?
No fix has been published for CVE-2026-3551 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-3551 being exploited?
There is no known exploitation of CVE-2026-3551 in the wild and no public exploit code.
Sources
Also known as GHSA-4xx2-h7jh-g7ph.