Companion Auto Update <= 3.9.2 - Authenticated (Administrator+) Stored Cross-Site Scripting via update_delay_days parameter
Strategic Overview
- Status
- Patched in 3.9.3
- Affected Plugin
- Companion Auto Update
- Affected Version
<= 3.9.2- CVSS
- 5.5Medium
- Weakness type
- CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
- CVE
CVE-2025-4369
At a glance
CVE-2025-4369 is a medium-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the Companion Auto Update WordPress plugin, affecting versions <= 3.9.2. It carries a CVSS score of 5.5 (reachable over the network; low attack complexity). Exploitation requires an authenticated account at Administrator level or above. The issue is fixed in version 3.9.3; sites on affected versions should update now. Disclosed July 2025, reported by Nabil Irawan.
Vulnerability Overview
The Companion Auto Update plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the ‘update_delay_days’ parameter in all versions up to, and including, 3.9.2 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with administrator-level access, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This only affects multi-site installations and installations where unfiltered_html has been disabled.
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 interaction from a victim user.
CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Companion Auto Update <= 3.9.2 carries this weakness at update_delay_days, and reaching it takes an account at Administrator level or above. Cross-site scripting happens when input from a request is written into a page without being escaped for the context it lands in, so the browser parses attacker-supplied text as markup or script.
Injected script runs with the privileges of whoever views the affected page, which is how these flaws turn into administrator session theft, silent account creation or persistent backdoors in page content. For Companion Auto Update the fix is 3.9.3: builds <= 3.9.2 are affected, anything from 3.9.3 onward is not.
Remediation
Update to version 3.9.3, or a newer patched version
How does WordSec protect against this?
An attacker needs Administrator access first, so the firewall sees the attempt as traffic from a logged-in account: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Companion Auto Update 3.9.3 closes this, and updating the plugin is the step that ends it.
- Firewall
- Alerts
External References
Related records
Vulnerability data © Defiant, Inc., provided under the Wordfence Intelligence T&C