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CVE-2026-70554— MaxSite CMS Unauthenticated PHP Object Injection via maxsite_comuser Cookie

Quick assessment

Affected
MaxSite MaxSite CMS
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

MaxSite CMS是MAX个人开发者开源的一款内容管理系统及组件集合。 MaxSite CMS 109.5及之前版本存在反序列化注入漏洞，该漏洞源于将maxsite_comuser cookie中攻击者控制的序列化数据直接传递给unserialize()函数且未进行验证或类允许列表，可能导致未经身份验证的攻击者通过构造恶意序列化对象触发魔术方法，利用SoapClient或Imagick等gadget链实现任意代码执行。

CVSS 9.8 · Critical EPSS 0.85% · P57

Affected Version Matrix 2

VendorProduct Version RangeStatus
MaxSite MaxSite CMS 0.78≤ 109.5 affected
109.6 unaffected
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I. Basic Information for CVE-2026-70554

Vulnerability Information
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Vulnerability Title
MaxSite CMS Unauthenticated PHP Object Injection via maxsite_comuser Cookie
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
可信数据的反序列化
Source: CVE Program / CVE List V5
Vulnerability Title
MaxSite CMS 反序列化漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
MaxSite CMS是MAX个人开发者开源的一款内容管理系统及组件集合。 MaxSite CMS 109.5及之前版本存在反序列化注入漏洞，该漏洞源于将maxsite_comuser cookie中攻击者控制的序列化数据直接传递给unserialize()函数且未进行验证或类允许列表，可能导致未经身份验证的攻击者通过构造恶意序列化对象触发魔术方法，利用SoapClient或Imagick等gadget链实现任意代码执行。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
MaxSite MaxSite CMS 0.78 ~ 109.5 -

II. Public POCs for CVE-2026-70554

# POC Description Source Link Shenlong Link
AI-Generated POC Premium
Qwen3.6-35B-A3B · 10518 chars
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III. Intelligence Information for CVE-2026-70554

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Vendor Advisories for CVE-2026-70554 (1)

Vendor Pages for CVE-2026-70554 (1)

Other References for CVE-2026-70554 (1)

Same Patch Batch · MaxSite · 2026-08-04 · 3 CVEs total

CVE-2026-70553 9.8 CRITICAL MaxSite CMS Unauthenticated RCE via Install Endpoint
CVE-2026-70552 9.8 CRITICAL MaxSite CMS 109.5 Unauthenticated AJAX Dispatcher Bypass via ajax.php

IV. Related Vulnerabilities

Same product: MaxSite CMS
Same vendor: MaxSite
Same weakness: CWE-502

V. Comments for CVE-2026-70554

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