by Kastro
Paper/Archive/CVE-2026-87930

CVE-2026-87930

MaxSite MaxSite CMS — MaxSite CMS through 109.6 PHP Object Injection via ci_session

EPSS 0.6%public exploitCVSS 9.2
critical.is priorityof 100
47
CVSS 9.2 (CNA)9.2 / 10 × 3027.6Not in CISA KEV+300.0EPSS percentile 49.0.490 × 209.8Exploit: SSVC poc+1010.0SSVC exploitation: poc+100.0
Description · from the CVE record

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.

Affected

ProductAffectedFixed inSource
MaxSite CMS0.78 – 109.6–CNA

Scores by source

VulnCheck (CNA)9.2CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
VulnCheck (CNA)8.1CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CISA ADPSSVCExploitation: poc · Automatable: no · Technical impact: total

References

refgithub.com/maxsite/cmsexploitgithub.com/EviL0rd/maxsite-cve6/blob/main/2026.09.08-maxsite-cms-unsafe-unserialize-object-injection.mdwriteupgithub.com/maxsite/cms/blob/2ca0a0c7d1d71106a25dbb0f2aedaaefbf12802c/system/libraries/Session.php#L670-L680writeupgithub.com/maxsite/cms/blob/2ca0a0c7d1d71106a25dbb0f2aedaaefbf12802c/system/libraries/Session.php#L740-L742writeupgithub.com/EviL0rd/maxsite-cve4/blob/main/2026.09.08-maxsite-cms-hardcoded-session-key-auth-bypass.mdwriteupgithub.com/maxsite/cms/blob/2ca0a0c7d1d71106a25dbb0f2aedaaefbf12802c/application/config/config.php#L230-L254writeupvulncheck.com/advisories/maxsite-cms-through-109.6-php-object-injection-via-ci-session