Custom CSS, JS & PHP <= 2.4.1 - Cross-Site Request Forgery to Remote Code Exectuiron
Strategic Overview
- Status
- Patched in 2.4.2
- Affected Plugin
- Custom CSS, JS & PHP
- Affected Version
<= 2.4.1- CVSS
- 8.8High
- Weakness type
- CWE-352 · Cross-Site Request Forgery (CSRF)
- CVE
CVE-2025-39601
At a glance
CVE-2025-39601 is a high-severity Cross-Site Request Forgery (CSRF) vulnerability in the Custom CSS, JS & PHP WordPress plugin, affecting versions <= 2.4.1. It carries a CVSS score of 8.8 (reachable over the network; low attack complexity; high confidentiality, integrity, availability impact). Exploitation requires no authentication. The issue is fixed in version 2.4.2; sites on affected versions should update now. Disclosed April 2025, reported by Nguyen Xuan Chien.
Vulnerability Overview
The Custom CSS, JS & PHP plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 2.4.1. This is due to missing or incorrect nonce validation on the save_options() function. This makes it possible for unauthenticated attackers to inject arbitrary code via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.
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. A successful exploit has high impact on confidentiality, integrity, availability — full site compromise territory.
CWE-352: Cross-Site Request Forgery (CSRF)
Custom CSS, JS & PHP <= 2.4.1 carries this weakness at save_options(), and reaching it takes a caller who can reach the endpoint. Cross-site request forgery abuses the fact that browsers attach a victim's cookies to any request, so a state-changing action that only checks who you are, not whether you meant to act, can be triggered from another site.
An attacker who gets a logged-in user to load a crafted page can perform that action as them, with the impact scaling to whatever the victim's role is allowed to do. For Custom CSS, JS & PHP the fix is 2.4.2: builds <= 2.4.1 are affected, anything from 2.4.2 onward is not.
Remediation
Update to version 2.4.2, or a newer patched version
How does WordSec protect against this?
The attempt arrives as an ordinary request to Custom CSS, JS & PHP: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Custom CSS, JS & PHP 2.4.2 closes this, and updating the plugin is the step that ends it.
- Firewall
- Alerts
External References
Related records
Other vulnerabilities in Custom CSS, JS & PHP
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