CVE-2026-8809
Published: 28 May 2026
Summary
CVE-2026-8809 is a critical-severity Improper Privilege Management (CWE-269) vulnerability in Wordpress (inferred from references). Its CVSS base score is 9.8 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked in the top 48.0% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-33165
Vulnerability details
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 —…
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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.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Direct unauthenticated exploitation of public WordPress plugin form leads to admin account creation via validation bypass (T1190 + T1068 + T1136.001).
CVEs Like This One
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Policy addresses roles, responsibilities, and privilege management to prevent improper privilege assignments.
Access supervision ensures privileges are assigned and managed without improper escalation or retention.
Assigning group/role memberships and access authorizations (privileges) while reviewing accounts addresses improper privilege management.
Enforces proper privilege management by requiring all decisions through the verified reference monitor.
By mandating division of duties across roles, the control enforces proper privilege management and prevents a single entity from controlling an entire sensitive process.
Implements core proper privilege management by restricting to only required rights.
Policy requires training on privilege management and least privilege, making it harder to exploit improper privilege management weaknesses.
Training covers proper privilege management practices, making incorrect privilege assignments less likely.