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4.4
CVE-2026-10100: Simple Custom Login Page plugin for WordPress: Unauthorized CSS Injection
CVE-2026-10100
Summary
The Simple Custom Login Page plugin for WordPress versions up to 1.0.3 allows attackers to inject malicious CSS code into the login page, which can be used to trick visitors into revealing their login credentials. This affects all sites using the plugin and is particularly concerning for sites with administrator-level access. To protect your site, update the plugin to a fixed version or remove it if possible.
Original title
The Simple Custom Login Page plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the color settings fields (Page Background, Form Background, Text Color, Link Color) in versions u...
Original description
The Simple Custom Login Page plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the color settings fields (Page Background, Form Background, Text Color, Link Color) in versions up to and including 1.0.3. This is due to insufficient input sanitization of the color option values (they were registered with register_setting() and stored via the Settings API/update_option() with no sanitize_callback) combined with the values being output into a <style> block on wp-login.php using esc_attr(), which is incorrect for a CSS context (it does not escape ;, {, }, / or *). This makes it possible for authenticated attackers, with administrator-level access and above, to inject arbitrary CSS rules into the login page that are rendered for all unauthenticated visitors, enabling UI-redress and credential-phishing attacks.
nvd CVSS3.1
4.4
Vulnerability type
CWE-79
Cross-site Scripting (XSS)
Published: 2 Jun 2026 · Updated: 2 Jun 2026 · First seen: 2 Jun 2026