A critical security vulnerability has been identified in the SureForms plugin for WordPress, potentially exposing websites to Cross-Site Request Forgery (CSRF) attacks. This blog post details the vulnerability, its potential impact, and how to mitigate the risk.
Overview
CVE-2025-12535 affects all versions of the SureForms plugin up to and including version 1.13.1. The vulnerability stems from the plugin’s improper use of WordPress REST API nonces, allowing unauthenticated attackers to bypass CSRF protection mechanisms. This oversight can lead to unauthorized actions being triggered on vulnerable websites.
Technical Details
The SureForms plugin utilizes WordPress’s REST API for handling form submissions. While the plugin legitimately needs to support unauthenticated form submissions, it incorrectly distributes generic WordPress REST API nonces (wp_rest) to unauthenticated users via the 'wp_ajax_nopriv_rest-nonce' action. This is the core of the problem.
Normally, WordPress uses nonces to prevent CSRF attacks by verifying that requests originate from legitimate user actions within the site. However, because SureForms uses a generic nonce instead of a form-specific one, an attacker can obtain a valid nonce and use it to craft malicious requests that appear to originate from an authorized user. REST API endpoints that rely solely on nonce verification, without additional authentication checks, become vulnerable.
The vulnerability lies in the fact that the exposed wp_rest nonce is not tied to any specific form. An attacker can leverage this to trigger the plugin’s post-submission hooks or potentially other plugins’ REST endpoints that rely on similar nonce-based validation. Key locations to inspect are:
inc/admin-ajax.php#L45: Location where thewp_ajax_nopriv_rest-nonceaction is registered.inc/background-process.php#L74: Example of potential usage of the vulnerable nonce.
CVSS Analysis
- CVSS Score: 5.3 (Medium)
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
A CVSS score of 5.3 indicates a medium severity vulnerability. The attack vector is network-based (AV:N), requiring no special network access. The attack complexity is low (AC:L), meaning it’s relatively easy to exploit. No privileges are required (PR:N) for the attacker to perform the attack. No user interaction (UI:N) is needed for successful exploitation. The scope is unchanged (S:U), indicating the attacker only affects the vulnerable component. The impact to confidentiality is none (C:N), the impact to integrity is low (I:L), and the impact to availability is none (A:N). This means a successful attack could modify some data on the site, but it doesn’t compromise confidentiality or availability in the traditional sense.
Possible Impact
Successful exploitation of this vulnerability could allow an attacker to:
- Trigger unauthorized post-submission actions within the SureForms plugin.
- Potentially manipulate form data or settings if no further authentication checks are in place.
- Exploit other plugins that improperly rely on the same generic nonce verification, leading to broader security compromises.
- Deface website
- Send Spam emails
Mitigation and Patch Steps
The recommended mitigation is to update the SureForms plugin to the latest available version, which contains a fix for this vulnerability. Specifically, update to a version *later* than 1.13.1. The fix involves using form-specific nonces instead of the generic wp_rest nonce.
You can update the plugin through the WordPress admin dashboard:
- Log in to your WordPress admin dashboard.
- Navigate to “Plugins” > “Installed Plugins.”
- Locate the SureForms plugin.
- Click “Update Now” if an update is available. If not, you may need to refresh your plugin list.
If an update is not immediately available, consider temporarily disabling the SureForms plugin until an updated version is released.
References
Stay vigilant and keep your WordPress plugins updated to protect your website from potential security threats.
