Theme Editor <= 3.0 - Cross-Site Request Forgery to Remote Code Execution
Strategic Overview
- Status
- Patched in 3.1
- Affected Plugin
- Theme Editor
- Affected Version
<= 3.0- CVSS
- 8.8High
- Weakness type
- CWE-352 · Cross-Site Request Forgery (CSRF)
- CVE
CVE-2025-9890
At a glance
CVE-2025-9890 is a high-severity Cross-Site Request Forgery (CSRF) vulnerability in the Theme Editor WordPress plugin, affecting versions <= 3.0. 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 3.1; sites on affected versions should update now. Disclosed October 2025, reported by Jonas Benjamin Friedli.
Vulnerability Overview
The Theme Editor plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 3.0. This is due to missing or incorrect nonce validation on the 'theme_editor_theme' page. This makes it possible for unauthenticated attackers to achieve remote code execution 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)
Theme Editor <= 3.0 carries this weakness at theme_editor_theme, 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 Theme Editor the fix is 3.1: builds <= 3.0 are affected, anything from 3.1 onward is not.
Remediation
Update to version 3.1, or a newer patched version
How does WordSec protect against this?
The attempt arrives as an ordinary request to Theme Editor: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Theme Editor 3.1 closes this, and updating the plugin is the step that ends it.
- Firewall
- Alerts
External References
Related records
Same weakness class
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