CVE-2026-1298: WordPress Easy Replace Image Auth Bypass

CVE-2026-1298 Overview

The Easy Replace Image plugin for WordPress contains a Missing Authorization vulnerability (CWE-862) in all versions up to and including 3.5.2. The vulnerability exists due to missing capability checks on the image_replacement_from_url function that is hooked to the eri_from_url AJAX action. This flaw allows authenticated attackers with Contributor-level access and above to replace arbitrary image attachments on the site with images from external URLs, potentially enabling site defacement, phishing attacks, or content manipulation.

Critical Impact

Authenticated attackers with minimal privileges (Contributor-level) can replace any image on the WordPress site with external content, enabling phishing, defacement, and malicious content injection.

Affected Products

• Easy Replace Image Plugin for WordPress versions ≤ 3.5.2
• WordPress installations using vulnerable Easy Replace Image versions

Discovery Timeline

• 2026-01-28 - CVE-2026-1298 published to NVD
• 2026-01-29 - Last updated in NVD database

Technical Details for CVE-2026-1298

Vulnerability Analysis

This vulnerability is classified as Missing Authorization (CWE-862), a common security flaw where access control checks are not properly implemented before performing sensitive operations. The vulnerable function image_replacement_from_url is exposed via the WordPress AJAX handler through the eri_from_url action but fails to verify whether the requesting user has the appropriate capabilities to modify image attachments.

The attack exploits the inherent trust model in WordPress where authenticated users are granted access to certain AJAX endpoints. Without proper capability verification, even low-privileged users such as Contributors can invoke the image replacement functionality that should be restricted to higher-privileged roles like Editors or Administrators.

Root Cause

The root cause of this vulnerability is the absence of WordPress capability checks (such as current_user_can()) within the image_replacement_from_url function before processing the image replacement request. The function directly processes incoming requests from any authenticated user without validating their authorization level to perform attachment modifications.

Attack Vector

The vulnerability is exploitable over the network by any authenticated user with at least Contributor-level privileges. An attacker can craft malicious AJAX requests to the eri_from_url action, specifying target attachment IDs and external image URLs. Upon successful exploitation, the attacker can:

1. Replace legitimate site images with malicious or inappropriate content
2. Insert phishing content disguised as legitimate site imagery
3. Deface the website by replacing branding or key visual elements
4. Manipulate product images in e-commerce scenarios for fraud

The attack does not require any user interaction beyond the initial authentication, and the changes persist until manually reverted by an administrator.

Detection Methods for CVE-2026-1298

Indicators of Compromise

• Unexpected changes to image attachments in the WordPress media library
• AJAX requests to admin-ajax.php with action parameter eri_from_url from Contributor-level users
• Image files being replaced with content sourced from external URLs
• Audit logs showing attachment modifications by users without Editor/Administrator roles

Detection Strategies

• Monitor WordPress AJAX requests for the eri_from_url action and correlate with user privilege levels
• Implement file integrity monitoring on the WordPress uploads directory to detect unauthorized image replacements
• Review web server access logs for suspicious patterns targeting admin-ajax.php with Easy Replace Image actions
• Deploy Web Application Firewall (WAF) rules to detect and alert on exploitation attempts

Monitoring Recommendations

• Enable WordPress audit logging to track all media library modifications with user attribution
• Configure alerts for image attachment changes made by users below Editor privilege level
• Monitor for connections to unexpected external URLs during image replacement operations
• Implement change detection on critical site images and branding assets

How to Mitigate CVE-2026-1298

Immediate Actions Required

• Update the Easy Replace Image plugin to a patched version (if available) that includes proper authorization checks
• If no patch is available, deactivate and remove the Easy Replace Image plugin until a fix is released
• Review WordPress media library for any unauthorized image replacements
• Audit user accounts with Contributor-level access and above for potential compromise

Patch Information

A fix for this vulnerability has been committed to the WordPress plugin repository. Administrators should update to the latest version of the Easy Replace Image plugin. For technical details on the changes, refer to the WordPress Plugin Changeset Details. Additional vulnerability information is available in the Wordfence Vulnerability Report.

Workarounds

• Disable the Easy Replace Image plugin entirely until a patched version is available
• Restrict user roles by removing Contributor-level access from untrusted users
• Implement server-side access controls to block AJAX requests to the eri_from_url action from non-admin users
• Use a security plugin to add capability checks to vulnerable AJAX endpoints

# Workaround: Block vulnerable AJAX action via .htaccess (Apache)
# Add to WordPress root .htaccess file
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{REQUEST_URI} ^.*wp-admin/admin-ajax\.php.*$ [NC]
RewriteCond %{QUERY_STRING} action=eri_from_url [NC]
RewriteRule .* - [F,L]
</IfModule>