CVE-2026-8809

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.

Source: NVD

References

• [NVD]https://nvd.nist.gov/vuln/detail/CVE-2026-8809
• [Other]https://plugins.trac.wordpress.org/browser/acf-extended/tags/0.9.2.4/includes/hooks.php#L636
• [Other]https://plugins.trac.wordpress.org/browser/acf-extended/tags/0.9.2.4/includes/module-acf.php#L141
• [Other]https://plugins.trac.wordpress.org/browser/acf-extended/tags/0.9.2.4/includes/modules/form/module-form-action-user.php#L715
• [Other]https://plugins.trac.wordpress.org/browser/acf-extended/tags/0.9.2.4/includes/modules/form/module-form-front.php#L94
• [Other]https://plugins.trac.wordpress.org/changeset/3551665/acf-extended
• [Other]https://www.wordfence.com/threat-intel/vulnerabilities/id/bd332f49-5aa9-4207-89db-84692a6430e0?source=cve

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