{"id":"CVE-2026-87929","title":"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","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 …","severity":"critical","cvss":9.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-321"],"vendor":"MaxSite","product":"MaxSite CMS","affected":["cms >= 0.78 <= 109.6"],"published":"2026-09-09","updated":"2026-09-14","sourceUpdated":"2026-09-14T14:17:18.670","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-87929","references":[{"url":"https://github.com/EviL0rd/maxsite-cve4/blob/main/2026.09.08-maxsite-cms-hardcoded-session-key-auth-bypass.md","label":"disclosure@vulncheck.com"},{"url":"https://github.com/maxsite/cms","label":"disclosure@vulncheck.com"},{"url":"https://github.com/maxsite/cms/blob/2ca0a0c7d1d71106a25dbb0f2aedaaefbf12802c/application/config/config.php#L230-L254","label":"disclosure@vulncheck.com"},{"url":"https://github.com/maxsite/cms/blob/2ca0a0c7d1d71106a25dbb0f2aedaaefbf12802c/application/maxsite/common/core/init.php#L70-L96","label":"disclosure@vulncheck.com"},{"url":"https://www.vulncheck.com/advisories/maxsite-cms-through-109.6-authentication-bypass-via-hardcoded-encryption-key","label":"disclosure@vulncheck.com"}],"tags":["nvd","cve.org","exploit-available"],"exploitAvailable":true,"ssvc":{"exploitation":"poc","automatable":"yes","technicalImpact":"total","timestamp":"2026-09-14T13:40:16.278801Z"},"epss":0.00288,"epssPercentile":0.21509,"ingestedAt":"2026-09-14T15:23:07.419Z","slug":"CVE-2026-87929","body":"## Overview\n\nMaxSite 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"abyssal","depthScore":66,"depthScoreParts":{"impact":53.9,"likelihood":0.1,"exploitation":12,"ransomware":0},"changes":[{"seq":200089,"id":"CVE-2026-87929","ts":1789395646807,"field":"exploit_available","old":"false","new":"true"}]}