{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-18116", "assignerOrgId": "ff5b8ace-8b95-4078-9743-eac1ca5451de", "state": "PUBLISHED", "assignerShortName": "ConcreteCMS", "dateReserved": "2026-07-28T18:02:00.045Z", "datePublished": "2026-09-14T22:05:49.140Z", "dateUpdated": "2026-09-14T22:05:49.140Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "ff5b8ace-8b95-4078-9743-eac1ca5451de", "shortName": "ConcreteCMS", "dateUpdated": "2026-09-14T22:05:49.140Z"}, "title": "Concrete CMS 8.3.0 to 9.5.2 is vulnerable to Stored XSS in Calendar Event Name via Workflow Approval Notifications", "problemTypes": [{"descriptions": [{"lang": "en", "cweId": "CWE-79", "description": "CWE-79 Improper Neutralization of Input During Web Page Generation", "type": "CWE"}]}], "impacts": [{"capecId": "CAPEC-592", "descriptions": [{"lang": "en", "value": "CAPEC-592 Stored XSS"}]}], "affected": [{"vendor": "Concrete CMS", "product": "Concrete CMS", "collectionURL": "https://github.com/concretecms/concretecms", "repo": "https://github.com/concretecms/concretecms", "versions": [{"status": "affected", "version": "8.3.0", "lessThanOrEqual": "9.5.2", "versionType": "git"}], "defaultStatus": "unaffected"}], "descriptions": [{"lang": "en", "value": "Concrete CMS 8.3.0 to 9.5.2 stored calendar event names without sanitization and rendered them without HTML escaping in the workflow approval and deletion notifications shown in the dashboard \"Waiting For Me\" block. A registered user permitted to add events to a calendar governed by an approval workflow could submit an event whose name contained a script payload, which then executed in an administrator's browser when the pending request was displayed and could be used to create a new administrator account.\u00a0The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 7.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N. Thanks v01demort for reporting.", "supportingMedia": [{"type": "text/html", "base64": false, "value": "<p><span>Concrete CMS 8.3.0 to 9.5.2 stored calendar event names without sanitization and rendered them without HTML escaping in the workflow approval and deletion notifications shown in the dashboard \"Waiting For Me\" block. A registered user permitted to add events to a calendar governed by an approval workflow could submit an event whose name contained a script payload, which then executed in an administrator's browser when the pending request was displayed and could be used to create a new administrator account.&nbsp;</span>The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 7.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N. Thanks v01demort for reporting.</p>"}]}], "references": [{"url": "https://documentation.concretecms.org/developers/introduction/version-history/953-release-notes", "tags": ["release-notes"]}], "metrics": [{"format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}], "cvssV4_0": {"attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "HIGH", "userInteraction": "PASSIVE", "vulnConfidentialityImpact": "HIGH", "subConfidentialityImpact": "NONE", "vulnIntegrityImpact": "HIGH", "subIntegrityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "version": "4.0", "baseSeverity": "HIGH", "baseScore": 7.3, "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"}}], "credits": [{"lang": "en", "value": "v01demort", "type": "finder"}], "source": {"defect": ["HackerOne"], "advisory": "3759240", "discovery": "EXTERNAL"}, "x_generator": {"engine": "Vulnogram 1.0.5"}}}}

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{"affected": [{"affectedData": [{"collectionURL": "https://github.com/concretecms/concretecms", "defaultStatus": "unaffected", "product": "Concrete CMS", "repo": "https://github.com/concretecms/concretecms", "vendor": "Concrete CMS", "versions": [{"lessThanOrEqual": "9.5.2", "status": "affected", "version": "8.3.0", "versionType": "git"}]}], "source": "ff5b8ace-8b95-4078-9743-eac1ca5451de"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Concrete CMS 8.3.0 to 9.5.2 stored calendar event names without sanitization and rendered them without HTML escaping in the workflow approval and deletion notifications shown in the dashboard \"Waiting For Me\" block. A registered user permitted to add events to a calendar governed by an approval workflow could submit an event whose name contained a script payload, which then executed in an administrator's browser when the pending request was displayed and could be used to create a new administrator account.\u00a0The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 7.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N. Thanks v01demort for reporting."}], "id": "CVE-2026-18116", "lastModified": "2026-09-14T23:17:15.683", "metrics": {"cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 7.3, "baseSeverity": "HIGH", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "privilegesRequired": "HIGH", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "PASSIVE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "version": "4.0", "vulnAvailabilityImpact": "HIGH", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "ff5b8ace-8b95-4078-9743-eac1ca5451de", "type": "Secondary"}]}, "published": "2026-09-14T23:17:15.683", "references": [{"source": "ff5b8ace-8b95-4078-9743-eac1ca5451de", "url": "https://documentation.concretecms.org/developers/introduction/version-history/953-release-notes"}], "sourceIdentifier": "ff5b8ace-8b95-4078-9743-eac1ca5451de", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-79"}], "source": "ff5b8ace-8b95-4078-9743-eac1ca5451de", "type": "Secondary"}]}

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