CVE-2026-81284 in ACF Extended Plugin
Summary
by MITRE • 08/28/2026
Contributor Broken Access Control in ACF Extended <= 0.9.2.6 versions.
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Analysis
by VulDB Data Team • 08/28/2026
The vulnerability identified as Contributor Broken Access Control within the ACF Extended plugin, specifically affecting versions up to and including 0.9.2.6, represents a critical failure in enforcing authorization policies for users with contributor-level privileges on WordPress installations. This flaw allows authenticated attackers who possess low-privilege accounts to perform actions that should be strictly reserved for administrators or higher-tier roles, thereby undermining the fundamental principle of least privilege essential for secure web application architecture. The issue stems from insufficient server-side validation when processing requests related to custom field configurations and data manipulation features provided by the plugin's extended functionality suite.
From a technical perspective, the vulnerability arises because the plugin fails to adequately verify whether the requesting user has sufficient permissions before executing sensitive operations such as modifying theme options or altering database structures associated with Advanced Custom Fields extensions. In many WordPress environments, contributor users are intended to have limited capabilities focused primarily on creating and editing their own posts without access to administrative settings. However, due to this broken access control mechanism, an attacker can exploit specific endpoints within the plugin's AJAX handlers or REST API integrations to bypass these restrictions. The lack of proper capability checks means that any authenticated user with a contributor role can interact with functions designed for administrators, leading to unauthorized state changes and potential data integrity issues across the website.
The operational impact of this vulnerability is significant as it enables privilege escalation from a low-level account to effectively gain administrative control over the WordPress instance. Once an attacker achieves this elevated status through the broken access control flaw, they can install malicious plugins, modify core files, inject backdoors into themes or templates, and exfiltrate sensitive user data including email addresses and password hashes stored in the database. This level of compromise not only jeopardizes the confidentiality and integrity of the website's content but also poses a severe risk to end-users who may have their personal information exposed through subsequent attacks facilitated by the compromised site infrastructure.
This vulnerability aligns closely with CWE-862, which describes Missing Authorization, as well as CWE-269 concerning Improper Privilege Management within the Common Weakness Enumeration framework. In terms of offensive security tactics, this flaw facilitates lateral movement and privilege escalation scenarios often categorized under MITRE ATT&CK technique T1078 Valid Accounts when combined with credential theft or initial access vectors like phishing. The exploitation path typically involves authenticating as a contributor user and then sending crafted HTTP requests to specific plugin endpoints that lack proper role verification logic, allowing the attacker to execute administrative commands without triggering standard WordPress security mechanisms designed to prevent such actions.
Mitigation strategies for this vulnerability require immediate action by website administrators to update the ACF Extended plugin to version 0.9.2.7 or later where these access control checks have been properly implemented and validated against current WordPress coding standards. Until an upgrade is possible, it is advisable to restrict contributor user accounts wherever feasible, ensuring that only trusted individuals with verified identities hold such privileges. Additionally, implementing a Web Application Firewall can provide an additional layer of defense by monitoring for anomalous request patterns associated with privilege escalation attempts targeting known vulnerable endpoints. Regular security audits and penetration testing should also be conducted to identify similar authorization flaws in other plugins or custom code within the WordPress ecosystem to maintain robust access control policies across all user roles.