Advanced Custom Fields: Extended PRO <= 0.9.2.6 - Unauthenticated Remote Code Execution via Dynamic Render Field Type
Strategic Overview
- Status
- Patched in 0.9.2.7
- Affected Plugin
- Advanced Custom Fields: Extended PRO
- Affected Version
<= 0.9.2.6- CVSS
- 9.8Critical
- Weakness type
- CWE-434 · Unrestricted Upload of File with Dangerous Type
- CVE
CVE pending
At a glance
This record tracks a critical-severity Unrestricted Upload of File with Dangerous Type vulnerability in the Advanced Custom Fields WordPress plugin, affecting versions <= 0.9.2.6. It carries a CVSS score of 9.8 (reachable over the network; low attack complexity; high confidentiality, integrity, availability impact). Exploitation requires no authentication. The issue is fixed in version 0.9.2.7; sites on affected versions should update now. Disclosed September 2026, reported by Tin Pham (TF1T).
Vulnerability Overview
The Advanced Custom Fields: Extended PRO plugin for WordPress is vulnerable to Limited Code Injection in all versions up to, and including, 0.9.2.6 via the render_field function. This is due to insufficient validation of form configuration parameters before merging into field settings and passing to call_user_func_array in the render_field method. This makes it possible for unauthenticated attackers to call arbitrary WordPress functions with controlled arguments. Method 1 requires the administrator to enable the non-default 'shortcode_preview' setting for the target form, while Method 2 requires the server environment to lack OpenSSL functions, causing ACF Pro's acf_decrypt to fall back to unverified base64 decoding.
Technical Analysis
The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no privileges on the target site, and no interaction from a victim user. A successful exploit has high impact on confidentiality, integrity, availability — full site compromise territory.
CWE-434: Unrestricted Upload of File with Dangerous Type
Advanced Custom Fields <= 0.9.2.6 carries this weakness at shortcode_preview, and reaching it takes no account at all. An unrestricted file upload lets a caller store a file whose type or destination the application does not properly constrain.
If an uploaded file lands anywhere the server will execute, the flaw becomes remote code execution and the site should be treated as fully compromised. For Advanced Custom Fields the fix is 0.9.2.7: builds <= 0.9.2.6 are affected, anything from 0.9.2.7 onward is not.
Remediation
Update to version 0.9.2.7, or a newer patched version
How does WordSec protect against this?
Requests carrying this pattern arrive without a session, so nothing upstream of the firewall gets a chance to reject them: WordSec's web application firewall inspects request payloads before WordPress loads them. Classes like this one can leave something behind, so the staged malware scanner is the second half: it looks for dropped files and modified code rather than for the request that created them. None of that substitutes for the fix: Advanced Custom Fields 0.9.2.7 closes this, and updating the plugin is the step that ends it.
- Firewall
- Scanner
- Login Security
External References
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