MaxSite CMS — CVE-2026-70554 (Critical)

Summary

MaxSite CMS contains a PHP object injection vulnerability that allows unauthenticated attackers to execute arbitrary code by passing attacker-controlled serialized data in the maxsite_comuser cookie directly to unserialize() without validation or class allowlisting. Attackers can craft a malicious serialized PHP object payload delivered in a single HTTP request to trigger magic methods during object graph reconstruction, enabling property-oriented programming attacks or remote code execution via available gadget chains such as those targeting SoapClient or Imagick extensions.

Why it matters

This CVE carries a CRITICAL severity rating (CVSS 9.8) in MaxSite CMS. Patch or mitigate promptly.

Operator check

Review CVE-2026-70554 in your asset inventory. Apply patches per vendor guidance and verify CMS is not exposed. CVSS score: 9.8.

Sources