CVE-2026-16259 Overview
CVE-2026-16259 is an authentication bypass vulnerability in the Uix UserCenter WordPress plugin through version 1.0.3. The plugin exposes an unauthenticated profile-update action that fails to verify ownership of the target account. It also validates the action with a token signed by a hardcoded key that is identical across every installation. Unauthenticated attackers can forge a valid token for any user, including administrators, and overwrite the account email and password. Successful exploitation yields full administrator takeover of the affected WordPress site. The weakness is categorized under CWE-269: Improper Privilege Management.
Critical Impact
Remote, unauthenticated attackers can take over any WordPress administrator account and gain full control of the site.
Affected Products
- Uix UserCenter WordPress plugin, all versions through 1.0.3
- WordPress sites with the plugin installed and activated
- Any hosting environment exposing the plugin's profile-update endpoint
Discovery Timeline
- 2026-08-29 - CVE-2026-16259 published to the National Vulnerability Database (NVD)
- 2026-08-31 - Last updated in the NVD database
Technical Details for CVE-2026-16259
Vulnerability Analysis
The Uix UserCenter plugin implements a profile-update workflow accessible without authentication. The handler accepts a user identifier and new profile values, including email address and password, from the request. It then applies those changes directly to the target account. The action is gated only by a token that the plugin validates against a signing key baked into the plugin source code. Because the same signing key ships with every installation, an attacker can generate a valid token off-site and submit it to any vulnerable server. The handler never checks that the token's subject matches the requester or that the requester owns the account being modified.
Root Cause
Two defects combine to produce full account takeover. First, the plugin uses a hardcoded, install-wide secret to sign authentication tokens, which violates secret uniqueness assumptions. Second, the profile-update action does not enforce an authorization check tying the current session to the account being modified. Together these flaws map to CWE-269, improper privilege management.
Attack Vector
An unauthenticated attacker computes a forged token using the hardcoded key extracted from the public plugin distribution. The attacker then submits a crafted profile-update request targeting the administrator user identifier, typically user ID 1. The request supplies attacker-controlled values for the account email and password. The server accepts the forged token, updates the administrator credentials, and the attacker authenticates as the administrator. See the WPScan Vulnerability Report for technical details.
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Stop Identity AttacksDetection Methods for CVE-2026-16259
Indicators of Compromise
- Unexpected changes to the user_email or user_pass fields of administrator accounts in the wp_users table.
- Successful administrator logins from previously unseen IP addresses immediately following a profile-update request.
- HTTP requests to the plugin's profile-update AJAX or REST endpoint from unauthenticated clients.
- Password reset or account recovery emails delivered to attacker-controlled addresses.
Detection Strategies
- Audit web server logs for POST requests to Uix UserCenter endpoints that lack an authenticated WordPress session cookie.
- Compare current administrator email addresses against a known-good baseline and alert on drift.
- Review WordPress activity logs, if installed, for profile_update events attributed to non-administrator or anonymous sources.
Monitoring Recommendations
- Forward WordPress and web server logs to a centralized analytics platform for correlation across sites.
- Alert on newly created administrator sessions that originate from IPs not previously associated with the account.
- Monitor outbound mail queues for password-change confirmation emails sent to unfamiliar recipients.
How to Mitigate CVE-2026-16259
Immediate Actions Required
- Deactivate and remove the Uix UserCenter plugin until a fixed release is available.
- Force a password reset for every administrator and privileged user on affected sites.
- Rotate WordPress authentication keys and salts in wp-config.php to invalidate existing sessions.
- Review the wp_users and wp_usermeta tables for unauthorized changes and restore known-good values.
Patch Information
No vendor patch is referenced in the enriched CVE data. The plugin is vulnerable through version 1.0.3. Consult the WPScan Vulnerability Report for updates on a fixed release. Until a patched version ships, treat the plugin as unsafe to run.
Workarounds
- Block requests to the plugin's profile-update endpoint at the web application firewall or reverse proxy.
- Restrict access to /wp-admin/admin-ajax.php and REST routes exposed by the plugin to authenticated administrators by IP allowlist.
- Remove the plugin directory from wp-content/plugins/ to guarantee the vulnerable handler cannot be reached.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
