CVE-2026-87929criticalCWE-321

CVE-2026-87929: critical vulnerability in MaxSite CMS

MaxSite CMS through 109.6 Authentication Bypass via Hardcoded Encryption Key

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48Vexday Risk Score

No sign of exploitation. It has a public proof of concept.

ssvc Attendcvss 9.3epss 0.5%
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:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Affected products
MaxSite · MaxSite CMS
⚠ Public resources, to assess the exposure of systems you control or are authorized to test. Test only with authorization.
Related CVEs — MaxSite CMS

In the same product, most dangerous first.

CVE-2026-70553CRITICALMaxSite CMS Unauthenticated RCE via Install EndpointEPSS 1.3%CVE-2026-70554CRITICALMaxSite CMS Unauthenticated PHP Object Injection via maxsite_comuser CookieEPSS 1.2%CVE-2026-70552CRITICALMaxSite CMS 109.5 Unauthenticated AJAX Dispatcher Bypass via ajax.phpEPSS 0.8%CVE-2026-87930CRITICALMaxSite CMS through 109.6 PHP Object Injection via ci_sessionEPSS 0.6%CVE-2026-87927HIGHMaxSite CMS through 109.6 Local File Inclusion via ajax dispatcherEPSS 0.6%CVE-2026-87928MEDIUMMaxSite CMS 0.94 through 109.6 HTML Upload XSS via admin_pageEPSS 0.3%