{"id":"CVE-2026-81905","title":"Concrete CMS below 9.5.3 stores user validation hashes for multiple purposes (email/registration validation, password reset, and persistent login) in a single table with a type column, but the redemption path resolves a hash by value alo…","summary":"Concrete CMS below 9.5.3 stores user validation hashes for multiple purposes (email/registration validation, password reset, and persistent login) in a single table with a type column, but the redemption path resolves a hash by value alo…","severity":"medium","cvss":6.3,"cvssVector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N","cwe":["CWE-640","CWE-863"],"vendor":"Concrete CMS","product":"Concrete CMS","affected":["concrete_cms >= 5.0.0 <= 9.5.2"],"published":"2026-09-11","updated":"2026-09-11","sourceUpdated":"2026-09-11T15:17:05.890","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-81905","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":"no","technicalImpact":"partial","timestamp":"2026-09-11T14:28:56.366688Z"},"cvssSource":"cna","ingestedAt":"2026-09-13T03:57:14.979Z","epss":0.00244,"epssPercentile":0.15879,"slug":"CVE-2026-81905","body":"## Overview\n\nConcrete CMS below 9.5.3 stores user validation hashes for multiple purposes (email/registration validation, password reset, and persistent login) in a single table with a type column, but the redemption path resolves a hash by value alone and does not verify its type. As a result, a hash issued for one purpose can be redeemed for another: a long-lived registration hash (60-day expiry) can be submitted to the password-change endpoint to set a new password on the target account, and a password-reset hash can be submitted to the email-validation endpoint to activate an account. Exploitation requires the attacker to first obtain a valid hash through a separate channel (for example email interception, log exposure, or SSRF against an internal mail relay), so the flaw amplifies the impact of any hash disclosure rather than creating a standalone entry point. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 6.3 with vector CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/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,"exploitation":0,"ransomware":0},"changes":[]}