{"id":"CVE-2026-81925","title":"Concrete CMS before 9.5.3 improperly neutralized a user-supplied custom date format when rendering conversation messages, resulting in reflected cross-site scripting","summary":"Concrete CMS before 9.5.3 improperly neutralized a user-supplied custom date format when rendering conversation messages, resulting in reflected cross-site scripting. An attacker could execute arbitrary JavaScript in the browser of a use…","severity":"medium","cvss":6.1,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","cwe":["CWE-79"],"vendor":"concretecms","product":"concrete_cms","affected":["concrete_cms < 9.5.3"],"patched":["concrete_cms 9.5.3"],"published":"2026-09-15","updated":"2026-09-21","sourceUpdated":"2026-09-21T17:53:13.887","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-81925","references":[{"url":"https://documentation.concretecms.org/developers/introduction/version-history/953-release-notes","label":"ff5b8ace-8b95-4078-9743-eac1ca5451de"}],"tags":["nvd","cve.org","score-dispute"],"epss":0.00414,"epssPercentile":0.35249,"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-09-16T17:46:17.138727Z"},"scores":{"nvd":6.1,"cna":2.1},"ingestedAt":"2026-09-15T20:44:02.417Z","slug":"CVE-2026-81925","body":"## Overview\n\nConcrete CMS before 9.5.3 improperly neutralized a user-supplied custom date format when rendering conversation messages, resulting in reflected cross-site scripting. An attacker could execute arbitrary JavaScript in the browser of a user who was tricked into submitting a crafted POST request to the conversation view endpoint. Exploitation was aided by the absence of a CSRF token on the endpoint, which allowed the payload to be delivered through an auto-submitting cross-origin POST without authentication. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 2.1 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Yonatan Drori from Tenzai for reporting.\n\n## Affected\n\n- `concrete_cms < 9.5.3`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `concrete_cms 9.5.3`","depth":"sunlit","depthScore":34,"depthScoreParts":{"impact":33.6,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[{"seq":208689,"id":"CVE-2026-81925","ts":1790016695337,"field":"cvss","old":"2.1","new":"6.1"},{"seq":208688,"id":"CVE-2026-81925","ts":1790016695337,"field":"severity","old":"low","new":"medium"}]}