CVE-2026-87930criticalCWE-502

CVE-2026-87930: critical vulnerability in MaxSite CMS

MaxSite CMS through 109.6 PHP Object Injection via ci_session

Published · Updated

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48Vexday Risk Score

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

ssvc Attendcvss 9.2epss 0.6%
from disclosure to weapon8 days
Published on NVDSep 9
1st PoC+8d
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.
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
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-2026-87927HIGHMaxSite CMS through 109.6 Local File Inclusion via ajax dispatcherEPSS 0.6%CVE-2026-87929CRITICALMaxSite CMS through 109.6 Authentication Bypass via Hardcoded Encryption KeyEPSS 0.5%CVE-2026-87928MEDIUMMaxSite CMS 0.94 through 109.6 HTML Upload XSS via admin_pageEPSS 0.3%