CVE-2026-8809

CRITICAL

Advanced Custom Fields: Extended <= 0.9.2.5 - Unauthenticated Privilege Escalation via Validation Bypass to '_acf_post_id' Parameter

Title source: cna
STIX 2.1

Exploitation Summary

EIP tracks 1 public exploit for CVE-2026-8809. PoCs published by izxci.

AI-analyzed exploit summary The repository contains a functional Python exploit for CVE-2026-8809, targeting an unauthenticated privilege escalation vulnerability in Advanced Custom Fields: Extended (ACF Extended) WordPress plugin. The exploit automates the process of creating an administrator account by bypassing validation checks via the '_acf_post_id' parameter.

Description

The Advanced Custom Fields: Extended plugin for WordPress is vulnerable to Privilege Escalation via Validation Bypass in all versions up to and including 0.9.2.5. The vulnerability exists due to the after_validate_save_post() function unconditionally trusting the attacker-controlled _acf_post_id POST parameter — with no authentication or integrity verification — to select a cleanup branch that silently discards all validation errors not prefixed with acfe:. This makes it possible for unauthenticated attackers to suppress both the role allow-list validation error added by acfe_field_user_roles::validate_front_value() and the administrator-role capability guard error added by acfe_module_form_action_user::validate_action(), causing wp_insert_user() to execute with an attacker-supplied administrator role argument and resulting in the creation of a new administrator-level user account. Exploitation requires the target site to expose a public ACFE frontend form configured with a Create User action that maps a role field.

Exploits (1)

github WORKING POC
by izxci · pythonpoc
https://github.com/izxci/CVE-2026-8809

The repository contains a functional Python exploit for CVE-2026-8809, targeting an unauthenticated privilege escalation vulnerability in Advanced Custom Fields: Extended (ACF Extended) WordPress plugin. The exploit automates the process of creating an administrator account by bypassing validation checks via the '_acf_post_id' parameter.

Classification
Working Poc 95%
Attack Type
Auth Bypass
Complexity
Moderate
Reliability
Reliable
Target: Advanced Custom Fields: Extended <= 0.9.2.5
No auth needed
Prerequisites: Target site running vulnerable ACF Extended plugin · Access to a form page with ACF fields
devstral-2 · analyzed Jun 12, 2026 Full analysis →

Scores

CVSS v3 9.8
EPSS 0.0049
EPSS Percentile 38.4%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CISA SSVC

Vulnrichment
Exploitation none
Automatable yes
Technical Impact total

Details

CWE
CWE-269
Status published
Products (1)
hwk-fr/Advanced Custom Fields: Extended < 0.9.2.5
Published May 28, 2026
Tracked Since May 29, 2026