CVE-2026-8809 Privilege escalation in Advanced Custom Fields: Extended
Unauthenticated attackers can create administrator accounts by bypassing validation in Advanced Custom Fields: Extended if a public user creation form is configured.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-8809?
CVE-2026-8809 is a critical vulnerability in hwk-fr Advanced Custom Fields: Extended, published on 28 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-269
Which versions are affected by CVE-2026-8809?
How do I fix CVE-2026-8809?
No fix has been published for CVE-2026-8809 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-8809 being exploited?
There is no known exploitation of CVE-2026-8809 in the wild and no public exploit code.
Public exploit code: 1 proofs of concept on GitHub.
Sources
Also known as GHSA-jvvq-c627-79xm.