MaxSite CMS through 109.6 passes the ci_session cookie to unserialize() without class restrictions, allowing unauthenticated attackers to inject PHP objects. Attackers can forge valid session cookies using the hardcoded encryption key to trigger magic methods and corrupt application state or achieve code execution if gadget classes exist.

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements Present

User Interaction None

Vulnerable System Confidentiality Impact High

Vulnerable System Integrity Impact High

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity High

Privileges Required None

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Exploitation poc

Automatable no

Technical Impact total

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
MaxSite MaxSite CMS unaffected
Version Status Constraints
0.78 affected ≤ 109.6

No data.

No data.

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No data.

Project Subscriptions

Vendors Products
Max-3000 Subscribe
Maxsite Cms Subscribe
Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://github.com/EviL0rd/maxsite-cve4/blob/main/2026.09.08-maxsite-cms-hardcoded-session-key-auth-bypass.md cve-icon cve-icon
https://github.com/EviL0rd/maxsite-cve6/blob/main/2026.09.08-maxsite-cms-unsafe-unserialize-object-injection.md cve-icon cve-icon
https://github.com/maxsite/cms cve-icon cve-icon
https://github.com/maxsite/cms/blob/2ca0a0c7d1d71106a25dbb0f2aedaaefbf12802c/application/config/config.php#L230-L254 cve-icon cve-icon
https://github.com/maxsite/cms/blob/2ca0a0c7d1d71106a25dbb0f2aedaaefbf12802c/system/libraries/Session.php#L670-L680 cve-icon cve-icon
https://github.com/maxsite/cms/blob/2ca0a0c7d1d71106a25dbb0f2aedaaefbf12802c/system/libraries/Session.php#L740-L742 cve-icon cve-icon
https://www.vulncheck.com/advisories/maxsite-cms-through-109.6-php-object-injection-via-ci-session cve-icon cve-icon
History

Wed, 09 Sep 2026 18:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Wed, 09 Sep 2026 17:00:00 +0000

Type Values Removed Values Added
Description MaxSite CMS through 109.6 passes the ci_session cookie to unserialize() without class restrictions, allowing unauthenticated attackers to inject PHP objects. Attackers can forge valid session cookies using the hardcoded encryption key to trigger magic methods and corrupt application state or achieve code execution if gadget classes exist.
Title MaxSite CMS through 109.6 PHP Object Injection via ci_session
First Time appeared Max-3000
Max-3000 maxsite Cms
Weaknesses CWE-502
CPEs cpe:2.3:a:max-3000:maxsite_cms:*:*:*:*:*:*:*:*
Vendors & Products Max-3000
Max-3000 maxsite Cms
References
Metrics cvssV3_1

{'score': 8.1, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H'}

cvssV4_0

{'score': 9.2, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-09-09T17:24:57.540Z

Reserved: 2026-09-09T16:12:38.084Z

Link: CVE-2026-87930

cve-icon Vulnrichment

Updated: 2026-09-09T17:24:52.802Z

cve-icon NVD

Status : Received

Published: 2026-09-09T17:17:53.990

Modified: 2026-09-09T18:17:06.623

Link: CVE-2026-87930

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-09T18:30:13Z

Weaknesses