CVE-2026-107506 Overview
CVE-2026-107506 affects the Simple Banner WordPress plugin in versions prior to 3.3.3. The plugin fails to correctly limit the capabilities it grants to user roles that an administrator permits to manage banners. Instead of a narrow banner-management capability, the plugin assigns the full administrator capability to those roles. Any authenticated user in a low-privileged role allowed to manage banners can escalate privileges and fully compromise the WordPress site. The flaw is categorized under [CWE-269] Improper Privilege Management.
Critical Impact
Authenticated low-privileged users with banner-management access gain full administrator rights, enabling complete site takeover.
Affected Products
- Simple Banner WordPress plugin versions prior to 3.3.3
- WordPress installations where an administrator granted non-admin roles the ability to manage Simple Banner banners
- Any site relying on WordPress role-based access control with Simple Banner installed
Discovery Timeline
- 2026-10-21 - CVE-2026-107506 published to NVD
- 2026-10-21 - Last updated in NVD database
Technical Details for CVE-2026-107506
Vulnerability Analysis
The Simple Banner plugin exposes a setting that lets administrators choose which WordPress roles are permitted to manage banners. The intent is to delegate banner editing to editors, authors, or custom roles without granting broader privileges. The implementation does not translate that intent into a scoped capability. Instead, selected roles receive the generic administrator capability check, which satisfies all permission gates across WordPress core and installed plugins.
Once a user holds the administrator capability, standard administrative actions become available. These include installing arbitrary plugins and themes, creating new administrator accounts, modifying site options, and executing PHP through theme or plugin editors. The result is full compromise of the WordPress instance from a role that should have been constrained to banner management.
Root Cause
The root cause is improper privilege management [CWE-269]. The plugin maps a feature-level permission to an overly broad WordPress capability. Rather than defining and checking a dedicated custom capability such as manage_simple_banners, the code grants or verifies the administrator capability to users in the configured roles. This collapses the principle of least privilege and makes the role selection equivalent to a role promotion.
Attack Vector
Exploitation requires an authenticated account in a role that the administrator has configured to manage banners. The attacker authenticates to WordPress, then invokes any administrator-restricted action through the admin dashboard or wp-admin endpoints. Because the plugin elevates the effective capability set, WordPress core treats requests from the attacker as administrator requests. From there, the attacker can upload a malicious plugin, modify theme files, or create a persistent admin account for later use. See the WPScan Vulnerability Report for additional technical context.
Detection Methods for CVE-2026-107506
Indicators of Compromise
- Creation of new WordPress user accounts with the administrator role from sessions belonging to non-admin users
- Unexpected plugin or theme installations shortly after a non-admin user logs in
- Modifications to wp-config.php, functions.php, or arbitrary PHP files via the WordPress file editor
- Changes to Simple Banner role configuration followed by privilege-sensitive actions from the newly permitted role
Detection Strategies
- Audit the Simple Banner settings to identify which non-admin roles are currently allowed to manage banners
- Correlate wp_users and wp_usermeta changes with the acting user's original role at the time of the action
- Review web server access logs for POST requests to /wp-admin/plugin-install.php, /wp-admin/theme-editor.php, and /wp-admin/users.php originating from non-admin sessions
Monitoring Recommendations
- Enable WordPress audit logging to capture role changes, user creation, and plugin or theme installation events
- Forward WordPress and web server logs to a centralized analytics platform for cross-session correlation
- Alert on any privilege escalation events where the acting account is not an original administrator
How to Mitigate CVE-2026-107506
Immediate Actions Required
- Update the Simple Banner plugin to version 3.3.3 or later on all WordPress sites
- Review Simple Banner settings and remove non-admin roles from the banner-management configuration until the patch is applied
- Audit the WordPress user list for unauthorized administrator accounts and revoke any that are not legitimate
- Rotate credentials for any accounts in roles that had banner-management privileges
Patch Information
The vendor has released Simple Banner version 3.3.3, which addresses the improper capability assignment. Upgrade through the WordPress plugin dashboard or by replacing the plugin files via WP-CLI. Confirm the installed version after the update and re-run a user and capability audit. Refer to the WPScan Vulnerability Report for advisory details.
Workarounds
- Restrict Simple Banner banner management to administrator accounts only until the plugin is upgraded
- Deactivate the Simple Banner plugin if updating is not immediately possible and banner functionality is non-critical
- Enforce multi-factor authentication for all WordPress accounts to reduce the risk of attacker-controlled low-privileged sessions
# Update Simple Banner using WP-CLI
wp plugin update simple-banner --version=3.3.3
wp plugin list --name=simple-banner --fields=name,version,status
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
