CVE-2026-18400: Slider, Gallery, and Carousel by MetaSlider <= 3.111.0 - Authenticated (Author+) Stored Cross-Site Scripting via 'delay' Post Meta Setting
The Slider, Gallery, and Carousel by MetaSlider – Image Slider, Video Slider plugin for WordPress is vulnerable to Stored Cross-Site Scripting via 'delay' Post Meta Setting in all versions up to, and including, 3.111.0 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with custom-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The ml-slider custom post type is registered without custom capability restrictions and the ml-slidersettings meta key is unprotected, allowing Author-level users to set the malicious delay value via XML-RPC customfields when creating an ml-slider post.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
WordPress plugin: Slider, Gallery, and Carousel by MetaSlider – Image Slider, Video Slider (MetaSlider)to a version that resolves this vulnerability.Fixed in 3.111.0 - Configuration
Protect/unprotect the ml-slider_settings meta key so it is not editable by lower-privileged users; prevent Author-level users from setting malicious delay values via XML-RPC custom_fields.
WordPress ml-slider custom post type ml-slider_settings meta key protection = protected - Compensating control
Apply capability restrictions for the ml-slider custom post type so that only trusted roles can create/edit ml-slider posts and set the ml-slider_settings meta key (prevents Author-level users from setting malicious values via XML-RPC custom_fields).
Event History
Frequently Asked Questions
What is the severity of CVE-2026-18400?
CVE-2026-18400 has a medium severity score of 6.4.
How do I fix CVE-2026-18400?
To fix CVE-2026-18400, update the Slider, Gallery, and Carousel by MetaSlider plugin to version 3.111.1 or later.
What type of vulnerability is CVE-2026-18400?
CVE-2026-18400 is classified as an Authenticated Stored Cross-Site Scripting (XSS) vulnerability.
What causes CVE-2026-18400?
CVE-2026-18400 is caused by insufficient input sanitization and output escaping in the 'delay' Post Meta Setting.
Who is affected by CVE-2026-18400?
All users of the Slider, Gallery, and Carousel by MetaSlider plugin up to version 3.111.0 are affected by CVE-2026-18400.