{"id":"CVE-2026-8809","state":"PUBLISHED","title":"Advanced Custom Fields: Extended <= 0.9.2.5 - Unauthenticated Privilege Escalation via Validation Bypass to '_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.","publishedAt":"2026-05-28T22:27:27.387Z","updatedAt":"2026-05-29T10:08:09.995Z","severity":{"score":9.8,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"Wordfence"},"assigner":"Wordfence","products":["hwk-fr Advanced Custom Fields: Extended"],"affected":[{"vendor":"hwk-fr","product":"Advanced Custom Fields: Extended","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThanOrEqual":"0.9.2.5","versionType":"semver"}]}],"references":["https://www.wordfence.com/threat-intel/vulnerabilities/id/bd332f49-5aa9-4207-89db-84692a6430e0?source=cve","https://plugins.trac.wordpress.org/browser/acf-extended/tags/0.9.2.4/includes/module-acf.php#L141","https://plugins.trac.wordpress.org/browser/acf-extended/tags/0.9.2.4/includes/hooks.php#L636","https://plugins.trac.wordpress.org/browser/acf-extended/tags/0.9.2.4/includes/modules/form/module-form-action-user.php#L715","https://plugins.trac.wordpress.org/browser/acf-extended/tags/0.9.2.4/includes/modules/form/module-form-front.php#L94","https://plugins.trac.wordpress.org/changeset/3551665/acf-extended"],"weaknesses":["CWE-269"],"ingestedAt":"2026-10-29T20:13:26.108Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/8xxx/CVE-2026-8809.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-8809","state":"PUBLISHED","datePublished":"2026-05-28T22:27:27.387Z","dateUpdated":"2026-05-29T10:08:09.995Z","assignerShortName":"Wordfence","assignerOrgId":"b15e7b5b-3da4-40ae-a43c-f7aa60e62599","dateReserved":"2026-05-18T06:34:31.899Z"},"containers":{"cna":{"title":"Advanced Custom Fields: Extended <= 0.9.2.5 - Unauthenticated Privilege Escalation via Validation Bypass to '_acf_post_id' Parameter","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"hwk-fr","product":"Advanced Custom Fields: Extended","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThanOrEqual":"0.9.2.5","versionType":"semver"}]}],"references":[{"url":"https://www.wordfence.com/threat-intel/vulnerabilities/id/bd332f49-5aa9-4207-89db-84692a6430e0?source=cve"},{"url":"https://plugins.trac.wordpress.org/browser/acf-extended/tags/0.9.2.4/includes/module-acf.php#L141"},{"url":"https://plugins.trac.wordpress.org/browser/acf-extended/tags/0.9.2.4/includes/hooks.php#L636"},{"url":"https://plugins.trac.wordpress.org/browser/acf-extended/tags/0.9.2.4/includes/modules/form/module-form-action-user.php#L715"},{"url":"https://plugins.trac.wordpress.org/browser/acf-extended/tags/0.9.2.4/includes/modules/form/module-form-front.php#L94"},{"url":"https://plugins.trac.wordpress.org/changeset/3551665/acf-extended"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-269","lang":"en","description":"CWE-269 Improper Privilege Management","type":"CWE"}]}],"providerMetadata":{"shortName":"Wordfence","orgId":"b15e7b5b-3da4-40ae-a43c-f7aa60e62599","dateUpdated":"2026-05-28T22:27:27.387Z"},"credits":[{"lang":"en","type":"finder","value":"daroo"}],"timeline":[{"time":"2026-05-27T10:28:29.000Z","lang":"en","value":"Vendor Notified"},{"time":"2026-05-28T10:09:02.000Z","lang":"en","value":"Disclosed"}]},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-05-29T10:03:00.555711Z","id":"CVE-2026-8809","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-05-29T10:08:09.995Z"}}]}}}