{"id":"CVE-2026-81906","title":"Concrete CMS OAuth callback login path prior to version 9.5.3 did not check whether an account was active or email-validated before establishing a session","summary":"Concrete CMS OAuth callback login path prior to version 9.5.3 did not check whether an account was active or email-validated before establishing a session. A deactivated or unvalidated user with an existing OAuth binding could complete a…","severity":"medium","cvss":6.3,"cvssVector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N","cwe":["CWE-288"],"vendor":"Concrete CMS","product":"Concrete CMS","affected":["concrete_cms >= 5.0.0 <= 9.5.2"],"published":"2026-09-11","updated":"2026-09-11","sourceUpdated":"2026-09-11T15:17:06.000","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-81906","references":[{"url":"https://documentation.concretecms.org/developers/introduction/version-history/953-release-notes","label":"ff5b8ace-8b95-4078-9743-eac1ca5451de"}],"tags":["nvd","cve.org"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"partial","timestamp":"2026-09-11T14:26:46.492008Z"},"cvssSource":"cna","epss":0.00617,"epssPercentile":0.47258,"ingestedAt":"2026-09-11T16:45:47.858Z","slug":"CVE-2026-81906","body":"## Overview\n\nConcrete CMS OAuth callback login path prior to version 9.5.3 did not check whether an account was active or email-validated before establishing a session. A deactivated or unvalidated user with an existing OAuth binding could complete authentication and receive a session that was fully authenticated for the callback response, with the login recorded and login events dispatched. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 6.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Yonatan Drori from Tenzai for reporting.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":35,"depthScoreParts":{"impact":34.7,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}