CVE-2026-2839
Received Received - Intake

Unauthenticated Data Access in Advanced Custom Fields Extended

Publication date: 2026-10-28

Last updated on: 2026-10-28

Assigner: Wordfence

Description
The Advanced Custom Fields: Extended plugin for WordPress is vulnerable to unauthorized access of data and triggering of server-side actions in all versions up to, and including, 0.9.2.7. This is due to multiple AJAX handlers registered for unauthenticated users (`wp_ajax_nopriv_*`) that fail to implement proper `current_user_can()` authorization checks. While these handlers use ACF's `acf_verify_ajax()` function to validate cryptographic nonces, the `acf_nonce` values are generated for guest users and publicly exposed in the page source of any frontend page utilizing an ACF form. This makes it possible for unauthenticated attackers to extract the guest nonce and bypass WordPress visibility permissions, leading to the unauthorized disclosure of post titles and internal Flexible Content layout structures. The vulnerability was partially patched in version 0.9.2.4.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published
2026-10-28
Last Modified
2026-10-28
Generated
2026-10-28
AI Q&A
2026-10-28
EPSS Evaluated
N/A
NVD
CVE-2026-2839
EUVD
EUVD-2026-111603

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
hwk-fr Advanced Custom Fields: Extended 0

Helpful Resources

Exploitability

CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-862 The product does not perform an authorization check when an actor attempts to access a resource or perform an action.

Attack-Flow Graph

AI Quick Actions

Instant insights powered by AI
Executive Summary

This vulnerability affects the Advanced Custom Fields: Extended WordPress plugin up to version 0.9.2.7. It allows unauthenticated users to access data and trigger server-side actions due to missing authorization checks in AJAX handlers. Attackers can extract public nonces from page source code to bypass permissions and view restricted post titles or internal content structures.

Detection Guidance

Check for the Advanced Custom Fields: Extended plugin version up to 0.9.2.7. Inspect frontend pages for exposed ACF nonces in page source. Use WordPress admin tools to review AJAX handlers for unauthenticated access.

Impact Analysis

An attacker could exploit this to view sensitive data like post titles or internal content layouts without authentication. While it does not allow data modification or deletion, unauthorized access to internal structures may lead to further exploitation or information leakage.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, potentially violating GDPR or HIPAA requirements for data protection and access controls. Organizations using this plugin must ensure proper access controls are enforced to maintain compliance.

Mitigation Strategies

Update the Advanced Custom Fields: Extended plugin to the latest version. Disable unauthenticated AJAX handlers if possible. Implement additional access controls for sensitive data exposure.

Chat Assistant

Ask questions about this CVE
Hi! I’m here to help you understand CVE-2026-2839. Ask me anything about the vulnerability, its impact, or mitigation strategies.
0/70

EPSS Chart