CVE-2026-70554Network attack vector

Unauthenticated code execution via serialized cookie

Published Aug 4, 2026 · Updated Aug 4, 2026

PHP object injection in MaxSite CMS 0.78 through 109.5 allows remote attackers to execute arbitrary code through a crafted cookie. The maxsite_comuser cookie is passed directly to PHP unserialize() without validation or class allowlisting, reconstructing attacker-controlled objects and invoking available magic methods. No authentication or user interaction is required; code execution depends on a usable gadget chain, including exposed SoapClient or Imagick classes.

CVSS severity9.3
Critical
EPSS probability0.85%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

PHP object injection in MaxSite CMS 0.78 through 109.5 allows remote attackers to execute arbitrary code through a crafted cookie. The maxsite_comuser cookie is passed directly to PHP unserialize() without validation or class allowlisting, reconstructing attacker-controlled objects and invoking available magic methods. No authentication or user interaction is required; code execution depends on a usable gadget chain, including exposed SoapClient or Imagick classes.

The record

CVE
CVE-2026-70554
Published
Aug 4, 2026
Updated
Aug 4, 2026
Vendor
MaxSite
Product
MaxSite CMS
Classifications
CWE-502, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 4, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0.78 <=109.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

MaxSite · MaxSite CMSversion=0.78 <=109.5

Published CVSS scores

9.3VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
9.8VulnCheckCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-502Deserialization of Untrusted Data
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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