CVE-2026-70554

Critical

Description

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.

SeverityCritical
CVSS9.8
Exploit probability—
ProductMaxSite CMS
PublishedAug 4, 2026
First seenAug 4, 2026

How to fix

Affected products

ProductAffected versionsFixed in
MaxSite MaxSite CMS0.78 ≤ v ≤ 109.5—

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