CVE-2026-70554

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.

CVSS 4.0

9.3CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CVSS 3.1

9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

1.2% chance of exploitation in the next 30 days; higher than 68% of CVEs (scores of 2026-10-25)

CWE

CWE-502

Published

2026-08-04

Modified

2026-10-24

Record from

the NVD, synced 2026-10-24

References

• https://github.com/maxsite/cms
• https://max-3000.com/page/maxsite-cms-109-6
• https://www.vulncheck.com/advisories/maxsite-cms-unauthenticated-php-object-injection-via-maxsite-comuser-cookie

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