External risk intelligence

WordPress SignUp & SignIn Plugin Authentication Bypass Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-12417

The vulnerability exists in a WordPress plugin that handles authentication and sign-in functionality. Such plugins are designed to be public-facing and reachable by anyone visiting the website, making them internet-accessible by default.

Authentication Bypass

Halo Surface Signal: 5 out of 5 — more likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A security issue has been identified in a WordPress plugin used for sign-up and sign-in functions. This vulnerability could allow unauthorized individuals to bypass authentication and take over user accounts, potentially leading to the compromise of administrative access on affected websites. The main concern is confirming the relevance and exposure of this plugin within our environment.

Weak password reset allows account takeover.
Critical access gained without credentials.
Confirm plugin usage and impact.

Attack Path

How an attacker could exploit the issue

An attacker can bypass authentication by sending a crafted request to the WordPress site's AJAX handler. This request targets the plugin's password reset functionality, which does not properly verify the reset code. By exploiting this, an attacker can change any user's password, leading to account takeover.

Accessible by unauthenticated users.
Weak validation of reset code.
Full account takeover possible.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could allow unauthenticated attackers to bypass password reset security and take over any user account on a WordPress site using the affected plugin. This could lead to an attacker gaining administrative privileges on the website.

WordPress user accounts.
Unauthenticated requests to `admin-ajax.php`.
Full website account takeover.

Operational Fix

Recommended remediation, mitigation, and detection steps

The security of your WordPress site relies on the collaboration between your application owners and infrastructure teams. The initial step is to identify all instances of the SignUp & SignIn plugin, assess their reachability and business criticality, and then pinpoint the accountable owner to plan remediation.

Application owners should address the issue.
Verify plugin usage and user impact.
Plan for vendor coordination and patching.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is the SignUp & SignIn plugin for WordPress?

It is an add-on component specifically designed to manage how users register for accounts and log into a WordPress website. By extending the core platform's capabilities, it handles authentication workflows, including the password reset processes that users rely on to regain access to their accounts.

How does CVE-2026-12417 create an authentication bypass?

This vulnerability, classified as CWE-640 (Weak Password Reset Validation), allows an attacker to manipulate the password reset mechanism. Because the plugin fails to verify the reset activation code and perform proper security checks, an attacker can supply empty values to successfully trigger a password change for any user on the system, granting them unauthorized access without ever needing a valid password or token.

Does a user need to have initiated a password reset for this to work?

No. In fact, the vulnerability is triggered most easily when a user has never requested a password reset. Because the code performs a loose equality check against an empty value, attackers can target any account where no prior reset metadata exists, effectively turning the absence of a security record into a mechanism for account compromise.

How do I know if my site is exposed to this flaw?

According to Halo Surface Signal, this plugin is designed for public-facing web functions, making it reachable to anyone on the internet by default. If your site uses this plugin and is accessible to the public, you should assume the vulnerable endpoint is reachable by external actors, regardless of whether your WordPress installation is intended for internal or external use.

What is the first step to address this CVE?

Your priority is to audit your WordPress environment to confirm if the SignUp & SignIn plugin is installed and active. Once identified, coordinate with the application owners to assess the risk to user accounts. Until you can update or replace the plugin, consider disabling the affected functionality if it is not business-critical to prevent potential unauthorized access.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.