CVE-2026-70554

MaxSite CMS Unauthenticated PHP Object Injection via maxsite_comuser Cookie

Published Aug 4, 2026 CVSS 4.0 · 9.3 Critical EPSS 1.2% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Max-3000
Max-3000 maxsite Cms
CPEs cpe:2.3:a:max-3000:maxsite_cms:*:*:*:*:*:*:*:*
Vendors & Products Max-3000
Max-3000 maxsite Cms
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Maxsite
Maxsite maxsite Cms
Vendors & Products Maxsite
Maxsite maxsite Cms
Type Values Removed Values Added
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.
Title MaxSite CMS Unauthenticated PHP Object Injection via maxsite_comuser Cookie
Weaknesses CWE-502
References
Metrics cvssV3_1

{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}

cvssV4_0

{'score': 9.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Sep 24, 2026, 2:18 PM
Reserved
Aug 4, 2026, 7:19 PM
Status
Deferred
Published
Aug 4, 2026, 9:16 PM
Modified
Oct 24, 2026, 3:10 PM