CVE-2026-76548: User Profile Builder Auth Bypass Vulnerability

CVE-2026-76548 Overview

CVE-2026-76548 affects the User Profile Builder WordPress plugin in versions prior to 4.0.1. The plugin fails to properly restrict its front-end file upload feature, granting unauthenticated visitors capabilities reserved for privileged roles. Attackers can enumerate the site's media library and modify unpublished posts, pages, and media items belonging to other users. The flaw is classified under CWE-287 (Improper Authentication) and exposes affected WordPress sites to content tampering and information disclosure over the network without user interaction.

Critical Impact
Unauthenticated attackers can list media assets and modify unpublished content owned by other users on affected WordPress installations.

Affected Products

User Profile Builder WordPress plugin versions prior to 4.0.1
WordPress sites exposing the plugin's front-end file upload feature
Any WordPress deployment with the vulnerable plugin activated

Discovery Timeline

2026-08-29 - CVE-2026-76548 published to the National Vulnerability Database (NVD)
2026-08-31 - Last updated in NVD database

Technical Details for CVE-2026-76548

Vulnerability Analysis

The User Profile Builder plugin exposes a front-end file upload feature intended for authenticated, privileged users. The feature does not enforce capability checks before processing requests. As a result, an unauthenticated visitor can invoke the same actions available to editor-class roles.

Two primary abuses follow from the missing authorization. First, the attacker can list the entire WordPress media library, exposing filenames and metadata that were not intended for public discovery. Second, the attacker can modify unpublished posts, pages, and media items owned by other users, enabling content tampering before publication.

The issue is network-exploitable and requires no privileges or user interaction. The confidentiality impact is limited to media library enumeration, while the integrity impact extends to modifying unpublished content across user boundaries.

Root Cause

The root cause is a missing authentication and capability check in the plugin's front-end file upload handler. The handler assumes calling context is a privileged user and dispatches privileged actions without validating the current user's role or the presence of a valid nonce tied to that role.

Attack Vector

Exploitation occurs over HTTP against the vulnerable plugin endpoint. An attacker sends crafted requests to the front-end upload handler on a target WordPress site. Because no authentication is required, the request is processed with elevated privileges, granting the attacker access to media enumeration and content modification actions. See the WPScan Vulnerability Report for additional technical detail.

Detection Methods for CVE-2026-76548

Indicators of Compromise

Unexpected modifications to unpublished posts, pages, or media items, particularly changes attributed to users who did not perform them
Unauthenticated HTTP POST requests targeting the User Profile Builder front-end upload endpoints
Anomalous listing or enumeration of media library items originating from external IPs

Detection Strategies

Inventory WordPress installations and identify sites running the User Profile Builder plugin at versions below 4.0.1
Review web server access logs for unauthenticated requests to plugin endpoints handling front-end uploads
Correlate WordPress audit logs with HTTP request logs to identify content modifications lacking a corresponding authenticated session

Monitoring Recommendations

Enable a WordPress activity logging plugin to record post, page, and media modifications with user attribution
Alert on repeated requests to plugin upload endpoints from a single source IP without a valid authenticated session cookie
Monitor for creation, modification, or deletion of media library items outside normal editorial workflows

How to Mitigate CVE-2026-76548

Immediate Actions Required

Update the User Profile Builder plugin to version 4.0.1 or later on all WordPress sites
Audit unpublished posts, pages, and media items for unauthorized modifications since the plugin was installed
Restrict access to the WordPress front-end forms exposing the vulnerable upload feature until patching is complete

Patch Information

Upgrade the User Profile Builder plugin to version 4.0.1 or later. This release enforces proper capability checks on the front-end file upload feature. Reference: WPScan Vulnerability Report.

Workarounds

Deactivate the User Profile Builder plugin until it can be updated to version 4.0.1 or later
Deploy a Web Application Firewall (WAF) rule that blocks unauthenticated requests to the plugin's front-end upload endpoints
Restrict access to pages hosting the vulnerable front-end forms using IP allowlisting or authentication at the reverse proxy layer

bash

# Example WP-CLI commands to identify and update the vulnerable plugin
wp plugin list --name=profile-builder --fields=name,status,version
wp plugin update profile-builder --version=4.0.1
wp plugin deactivate profile-builder  # if immediate patching is not possible