CVE-2026-87929

MaxSite CMS through 109.6 Authentication Bypass via Hardcoded Encryption Key

Published: Sep 9, 2026Updated: Sep 14, 2026 Sources: CVE List NVDCWE-321

9.8CRITICAL

Description

MaxSite CMS through 109.6 ships with a hardcoded session encryption key in application/config/config.php that is never changed during installation, allowing unauthenticated attackers to forge administrator session cookies. Attackers can mint a malicious ci_session cookie with administrator privileges by computing an HMAC-SHA1 using the publicly known encryption key, bypassing authentication checks in is_login() and mso_check_allow() functions.

No summary for this CVE yet.

CVSS Vector Breakdown

Exploitability

AV:NAttack Vector

Network

AC:LAttack Complexity

Low

PR:NPrivileges Required

None

UI:NUser Interaction

None

Scope

S:UScope

Unchanged

Impact

C:HConfidentiality

High

I:HIntegrity

High

A:HAvailability

High

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Weaknesses

CWE-321

Affected Products

MaxSite

commercialaka maxsite cms

MaxSite CMSOn-prem

Web & CMS Plugins / cms-core

Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

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References

https://github.com/EviL0rd/maxsite-cve4/blob/main/2026.09.08-maxsite-cms-hardcoded-session-key-auth-bypass.md

github.com

https://github.com/maxsite/cms

github.com

https://github.com/maxsite/cms/blob/2ca0a0c7d1d71106a25dbb0f2aedaaefbf12802c/application/config/config.php#L230-L254

github.com

and 2 more references View all →

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