CVE-2026-70553 MaxSite CVE debrief

Who should care

Administrators and users of MaxSite CMS, as well as security teams and IT professionals responsible for maintaining and securing web applications, should be aware of this critical vulnerability and take immediate action to assess and mitigate potential risks.

Technical summary

The MaxSite CMS contains a remote code execution vulnerability that allows unauthenticated attackers to inject arbitrary PHP code into the application configuration file. This is achieved by submitting crafted POST requests to the install endpoint after installation is complete. The vulnerability can be exploited by supplying a malicious db_dbprefix value containing a single quote to break out of a PHP string literal in application/config/database.php, appending attacker-controlled PHP statements that are executed by the web server on every subsequent request, resulting in persistent unauthenticated remote code execution as the web-server process user.

Defensive priority

CVE-2026-70553 is a critical vulnerability in MaxSite CMS with a CVSS score of 9.3, allowing unauthenticated remote code execution. Immediate attention is required to assess and mitigate potential risks.

Recommended defensive actions

• Review and assess the MaxSite CMS installation for potential exposure
• Apply patches or updates to fix the vulnerability
• Implement additional security measures to detect and prevent similar attacks
• Monitor the system for suspicious activity
• Consider compensating controls to mitigate potential risks

Evidence notes

The CVE description indicates that MaxSite CMS contains a remote code execution vulnerability allowing unauthenticated attackers to inject arbitrary PHP code. The vulnerability is caused by improper handling of user input in the install endpoint, which can be exploited by submitting crafted POST requests. The CVSS score of 9.3 indicates a critical vulnerability.

Official resources