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TI-2026-59994 Aliases CVE-2026-87929GHSA-x43r-8q5x-82p8

MaxSite CMS through 109.6 Authentication Bypass via Hardcoded Encryption Key

Priority HIGH 81CWE-321Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
Security bypass
Confidentiality · integrity · availability
High · High · High
Fix status
No fix listed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-321.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00527 44th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by the CNA
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
MaxSiteMaxSite CMS0.78 – 109.6—No fix listedCNA
  • MaxSite CMS VendorMaxSite Affected 0.78 – 109.6 Fixed in — No fix listed CNA

Remediation

No fixed version listed by the sources yet.

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-87929
  2. 2026-10-03 Alias added: GHSA-x43r-8q5x-82p8

References

Exploit 1

Other 3

  • TI-2026-59992 MaxSite CMS through 109.6 Local File Inclusion via ajax dispatcher CVSS 4.0HIGH 8.8
  • TI-2026-59995 MaxSite CMS through 109.6 PHP Object Injection via ci_session CVSS 4.0CRITICAL 9.2
  • TI-2026-02931 MaxSite CMS MarkItUp Preview AJAX Endpoint preview-ajax.php eval code injection CVSS 4.0MEDIUM 6.9
  • TI-2025-11324 MaxSite CMS save-file-ajax.php unrestricted upload CVSS 4.0MEDIUM 5.3
  • TI-2026-06140 MaxSite CMS ushki Plugin cross site scripting CVSS 4.0MEDIUM 4.8
  • TI-2026-06139 MaxSite CMS Guestbook Plugin cross site scripting CVSS 4.0MEDIUM 4.8
See all 18 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences