CVE-2026-25425: User Registration Auth Bypass Flaw

CVE-2026-25425 Overview

CVE-2026-25425 is an unauthenticated broken access control vulnerability affecting the WordPress User Registration plugin in versions 5.1.2 and earlier. The flaw is classified under [CWE-862] Missing Authorization and allows remote attackers to interact with restricted plugin functionality without providing credentials. According to the Patchstack advisory, the vulnerability impacts availability of the affected WordPress site. The issue is exploitable over the network with low attack complexity and requires no user interaction.

Critical Impact
Remote, unauthenticated attackers can bypass access controls in the User Registration plugin and trigger actions that disrupt site availability on WordPress installations running version 5.1.2 or earlier.

Affected Products

WordPress User Registration plugin versions <= 5.1.2
WordPress sites using the User Registration plugin for account management
WordPress deployments that expose plugin endpoints without additional access restrictions

Discovery Timeline

2026-06-15 - CVE-2026-25425 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2026-25425

Vulnerability Analysis

The vulnerability stems from missing authorization checks in the User Registration plugin for WordPress. Plugin endpoints fail to verify whether the requester holds the necessary capability or role before executing privileged actions. This omission allows unauthenticated network requests to invoke functionality the plugin should restrict.

The impact profile focuses on availability rather than data confidentiality or integrity. An attacker abusing the exposed action can degrade or disrupt service for legitimate users of the WordPress site. The Patchstack report tracks this as a broken access control issue affecting all versions through 5.1.2.

The Exploit Prediction Scoring System (EPSS) places exploitation probability at 0.372%, indicating low but non-trivial near-term exploitation likelihood. No public proof-of-concept and no known in-the-wild exploitation have been reported at publication time.

Root Cause

The root cause is a missing authorization check [CWE-862]. The plugin registers an action handler that does not validate the caller's identity or capabilities before performing state-changing operations. Without current_user_can() or equivalent capability checks, the handler treats anonymous requests as authorized.

Attack Vector

Exploitation occurs over the network against the WordPress site hosting the vulnerable plugin. An attacker sends a crafted HTTP request to the exposed plugin endpoint. Because no authentication or capability check is performed, the server executes the requested operation. Refer to the Patchstack Vulnerability Report for endpoint-level technical details.

Detection Methods for CVE-2026-25425

Indicators of Compromise

Anomalous unauthenticated POST or GET requests targeting User Registration plugin endpoints under /wp-admin/admin-ajax.php or /wp-json/
Unexpected availability degradation, slow responses, or error spikes on WordPress sites running the plugin
Web server logs showing repeated requests to plugin actions from a single source without authentication cookies

Detection Strategies

Inventory WordPress installations and confirm the installed version of the User Registration plugin against the vulnerable range (<= 5.1.2)
Inspect access logs for requests to plugin AJAX or REST routes that lack a valid wordpress_logged_in_* cookie or nonce
Correlate spikes in 4xx/5xx response codes with requests to User Registration endpoints to identify probing or abuse

Monitoring Recommendations

Forward WordPress and web server logs to a centralized analytics platform for query-based hunting on plugin endpoints
Configure alerts for unauthenticated requests to administrative or registration endpoints from external IPs
Track plugin file integrity and version metadata to detect outdated installations across managed sites

How to Mitigate CVE-2026-25425

Immediate Actions Required

Update the WordPress User Registration plugin to a version newer than 5.1.2 as soon as a fixed release is available from the vendor
Audit all WordPress sites under management for the affected plugin and prioritize internet-facing installations
Review web application firewall rules to block anonymous requests to plugin AJAX and REST endpoints

Patch Information

Consult the Patchstack Vulnerability Report for the current patched version and vendor guidance. Apply the vendor-supplied update through the WordPress plugin manager or via wp-cli once available.

Workarounds

Temporarily disable the User Registration plugin on sites where the affected functionality is not required
Restrict access to /wp-admin/admin-ajax.php actions related to the plugin using web server or WAF rules until patched
Limit network exposure of WordPress administrative endpoints to trusted IP ranges where feasible

bash

# Configuration example: update the plugin via wp-cli once a fixed version is published
wp plugin update user-registration --version=<fixed-version>
wp plugin status user-registration