Privilege escalation via unsanitized custom style values
Published Sep 14, 2026 · Updated Sep 14, 2026
Stored XSS in Concrete CMS before 9.5.3 allows remote authenticated users to execute script in an administrator's session. The Block Design dialog writes unsanitized custom style values into page CSS through a DOM sink, preserving attacker-controlled script. Editor-level access is required, and execution occurs when an administrator renders the stored page content, enabling privilege escalation.
Summary
What happened
Stored XSS in Concrete CMS before 9.5.3 allows remote authenticated users to execute script in an administrator's session. The Block Design dialog writes unsanitized custom style values into page CSS through a DOM sink, preserving attacker-controlled script. Editor-level access is required, and execution occurs when an administrator renders the stored page content, enabling privilege escalation.
The record
- CVE
- CVE-2026-18119
- Published
- Sep 14, 2026
- Updated
- Sep 14, 2026
- Vendor
- Concrete CMS
- Product
- Concrete CMS
- Classifications
- T1068
- 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=5.0.0 <=9.5.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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