Administrator account creation via calendar event XSS
Published Sep 14, 2026 · Updated Sep 14, 2026
Stored XSS in Concrete CMS 8.3.0 through 9.5.2 allows remote authenticated users to execute script in an administrator's browser. Calendar event names are stored without sanitization and rendered without HTML escaping in workflow approval and deletion notifications within the dashboard workflow queue. Exploitation requires permission to add events to an approval-governed calendar and an administrator to display the pending request; the script can create a new administrator account.
Summary
What happened
Stored XSS in Concrete CMS 8.3.0 through 9.5.2 allows remote authenticated users to execute script in an administrator's browser. Calendar event names are stored without sanitization and rendered without HTML escaping in workflow approval and deletion notifications within the dashboard workflow queue. Exploitation requires permission to add events to an approval-governed calendar and an administrator to display the pending request; the script can create a new administrator account.
The record
- CVE
- CVE-2026-18116
- Published
- Sep 14, 2026
- Updated
- Sep 14, 2026
- Vendor
- Concrete CMS
- Product
- Concrete CMS
- Classifications
- CWE-79, T1059.007
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Sep 14, 2026CVE publishedPublication date reported by the CVE source.
- Sep 14, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=8.3.0 <=9.5.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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