CVE-2026-87929: Use of Hard-coded Cryptographic Key in MaxSite MaxSite CMS
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.
CVSS v4.0
Score 9.3critical
Affected software
MaxSite
MaxSite CMS
Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-87929 describes a vulnerability in MaxSite CMS through version 109.6 where a hardcoded cryptographic key used for session encryption is embedded in application/config/config.php and remains unchanged during installation. Attackers can exploit this by creating a malicious ci_session cookie with administrator privileges by computing an HMAC-SHA1 using the publicly known key. This bypasses authentication functions is_login() and mso_check_allow(), allowing unauthorized administrative access.
Potential Impact
The vulnerability enables unauthenticated attackers to gain administrator-level access to the MaxSite CMS by forging session cookies. This compromises the integrity and confidentiality of the CMS, potentially allowing full control over the affected system without any authentication.
Mitigation Recommendations
No patch or official fix information is provided in the input data. Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, users should consider restricting access to the CMS or implementing additional authentication controls to mitigate risk.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-09-09T16:12:31.422Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6aa18eeaacd9273b499ae5d1
Added to database: 09/09/2026, 16:52:58 UTC
Last enriched: 09/25/2026, 02:48:50 UTC
Last updated: 10/10/2026, 06:48:20 UTC
Views: 66
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.