CVE-2025-13486

Advanced Custom Fields: Extended 0.9.0.5 - 0.9.1.1 - Unauthenticated Remote Code Execution in prepare_form

2025-12-02 18:43
Marcin Dudek (dudekmar)

Strategic Overview

Status
Patched in 0.9.2
Affected Plugin
Advanced Custom Fields: Extended
Affected Version
0.9.0.5 – 0.9.1.1
CVSS
9.8Critical
Weakness type
CWE-94 · Improper Control of Generation of Code ('Code Injection')
CVE
CVE-2025-13486
View all Advanced Custom Fields: Extended vulnerabilities

At a glance

CVE-2025-13486 is a critical-severity Improper Control of Generation of Code ('Code Injection') vulnerability in the Advanced Custom Fields WordPress plugin, affecting versions 0.9.0.5 – 0.9.1.1. 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; sites on affected versions should update now. Disclosed December 2025, reported by Marcin Dudek (dudekmar).

Vulnerability Overview

The Advanced Custom Fields: Extended plugin for WordPress is vulnerable to Remote Code Execution in versions 0.9.0.5 through 0.9.1.1 via the prepare_form() function. This is due to the function accepting user input and then passing that through call_user_func_array(). This makes it possible for unauthenticated attackers to execute arbitrary code on the server, which can be leveraged to inject backdoors or create new administrative user accounts.

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-94: Improper Control of Generation of Code ('Code Injection')

Advanced Custom Fields 0.9.0.5 – 0.9.1.1 carries this weakness at prepare_form(), and reaching it takes no account at all. Code injection means input from a request reaches a language construct that evaluates code, so the attacker's text is executed rather than treated as data.

The injected code runs with the web server's privileges, giving the attacker the same access to the database and filesystem as WordPress itself. For Advanced Custom Fields the fix is 0.9.2: builds 0.9.0.5 – 0.9.1.1 are affected, anything from 0.9.2 onward is not.

Remediation

Update to version 0.9.2, 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 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Scanner
  • Login Security

External References

https://www.cve.org/CVERecord?id=CVE-2025-13486https://www.wordfence.com/threat-intel/vulnerabilities/id/c508cb73-53e6-4ebe-b3d0-285908b722c9https://nvd.nist.gov/vuln/detail/CVE-2025-13486

Related records

Vulnerability data © Defiant, Inc., provided under the Wordfence Intelligence T&C