CVE-2026-25393: Hello FSE Auth Bypass Vulnerability

CVE-2026-25393 Overview

CVE-2026-25393 is a Missing Authorization vulnerability affecting the Hello FSE WordPress theme developed by sparklewpthemes. This broken access control vulnerability allows authenticated attackers to exploit incorrectly configured access control security levels, potentially enabling unauthorized modifications to site content or settings.

The vulnerability stems from CWE-862 (Missing Authorization), where the theme fails to properly validate user permissions before allowing certain actions. This allows low-privileged users to perform operations that should be restricted to higher privilege levels.

Critical Impact

Authenticated users with minimal privileges can bypass access controls to make unauthorized changes within WordPress installations running the vulnerable Hello FSE theme.

Affected Products

• Hello FSE WordPress Theme versions through 1.0.6
• WordPress installations using the Hello FSE theme by sparklewpthemes

Discovery Timeline

• 2026-02-19 - CVE-2026-25393 published to NVD
• 2026-02-19 - Last updated in NVD database

Technical Details for CVE-2026-25393

Vulnerability Analysis

This vulnerability is classified as a Missing Authorization flaw (CWE-862) in the Hello FSE WordPress theme. The theme fails to implement proper capability checks before executing privileged operations, allowing authenticated users to bypass intended access restrictions.

The attack requires network access and low-level authentication (such as a subscriber role), but no user interaction is needed. While the vulnerability does not allow data exfiltration or cause availability issues, it does permit unauthorized integrity modifications to the WordPress installation.

Root Cause

The root cause is the absence of proper authorization checks within the Hello FSE theme's functionality. WordPress themes should implement capability checks using functions like current_user_can() to verify that the requesting user has appropriate permissions before executing sensitive operations. The Hello FSE theme version 1.0.6 and earlier versions fail to perform these authorization validations consistently.

Attack Vector

The attack vector is network-based, requiring an authenticated session. An attacker would need to:

1. Obtain valid credentials for any user role on the target WordPress site (even minimal roles like Subscriber)
2. Identify endpoints or AJAX handlers in the Hello FSE theme that lack authorization checks
3. Craft requests to these unprotected endpoints to perform actions beyond their assigned role permissions

The vulnerability allows exploitation of incorrectly configured access control security levels, meaning attackers can escalate their effective permissions within the theme's functionality without actually elevating their WordPress role.

Detection Methods for CVE-2026-25393

Indicators of Compromise

• Unexpected modifications to theme settings or customizations by non-administrator users
• Audit logs showing theme-related actions performed by users without appropriate permissions
• Unusual AJAX requests to Hello FSE theme endpoints from low-privileged user sessions

Detection Strategies

• Review WordPress audit logs for theme modifications by users with subscriber, contributor, or author roles
• Monitor for unusual patterns of requests to theme-specific endpoints or AJAX handlers
• Implement file integrity monitoring on theme configuration files
• Use WordPress security plugins that log and alert on suspicious user activities

Monitoring Recommendations

• Enable comprehensive audit logging for all WordPress user actions
• Monitor authentication events for accounts that subsequently access theme functionality
• Set up alerts for any theme customization changes made outside of normal administrative workflows
• Regularly review user role assignments to ensure principle of least privilege

How to Mitigate CVE-2026-25393

Immediate Actions Required

• Update the Hello FSE theme to a patched version when available from sparklewpthemes
• Review user accounts and remove unnecessary privileges from accounts that do not require them
• Temporarily disable the Hello FSE theme and switch to a default WordPress theme if the theme is not critical to operations
• Audit recent theme changes to identify any unauthorized modifications

Patch Information

Users should check with sparklewpthemes for an updated version of the Hello FSE theme that addresses this vulnerability. The Patchstack WordPress Vulnerability Report provides additional details on this vulnerability.

Until a patch is available, consider implementing the workarounds listed below to reduce exposure.

Workarounds

• Restrict user registration on WordPress sites running the vulnerable theme to prevent attackers from easily obtaining authenticated access
• Use a WordPress security plugin to add additional authorization layers and capability checks
• Limit login access to trusted IP addresses using .htaccess rules or a security plugin
• Remove or demote unnecessary user accounts to reduce the attack surface

# Example: Restrict WordPress admin access by IP in .htaccess
<Files wp-login.php>
    Order Deny,Allow
    Deny from all
    Allow from 192.168.1.0/24
    Allow from your.trusted.ip.address
</Files>