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

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Summary

CVECVE-2026-8809
StatePUBLISHED
AssignerWordfence
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-28 23:16:44 UTC
Updated2026-05-29 02:40:08 UTC
DescriptionThe 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.

Risk And Classification

Primary CVSS: v3.1 9.8 CRITICAL from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Problem Types: CWE-269 | CWE-269 CWE-269 Improper Privilege Management

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Hwk-fr Advanced Custom Fields Extended affected 0.9.2.5 semver Not specified

References

ReferenceSourceLinkTags
plugins.trac.wordpress.org/browser/acf-extended/tags/0.9.2.4/includes/hooks.php [email protected] plugins.trac.wordpress.org
plugins.trac.wordpress.org/changeset/3551665/acf-extended [email protected] plugins.trac.wordpress.org
plugins.trac.wordpress.org/browser/acf-extended/tags/0.9.2.4/includes/modules/form/modul... [email protected] plugins.trac.wordpress.org
www.wordfence.com/threat-intel/vulnerabilities/id/bd332f49-5aa9-4207-89db-84692... [email protected] www.wordfence.com
plugins.trac.wordpress.org/browser/acf-extended/tags/0.9.2.4/includes/module-acf.php [email protected] plugins.trac.wordpress.org
plugins.trac.wordpress.org/browser/acf-extended/tags/0.9.2.4/includes/modules/form/modul... [email protected] plugins.trac.wordpress.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: daroo (en)

Additional Advisory Data

SourceTimeEvent
CNA2026-05-27T10:28:29.000ZVendor Notified
CNA2026-05-28T10:09:02.000ZDisclosed
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