# CVE-2026-18119

## Summary

- **CVE ID:** CVE-2026-18119
- **Severity:** HIGH
- **CVSS Score:** 7 (CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:L/VI:H/VA:H/SC:N/SI:N/SA:N)
- **CWE:** CWE-79
- **Published:** Sep 14, 2026
- **Last Modified:** Sep 14, 2026

## Description

Concrete CMS below 9.5.3 did not sanitize custom style values in the Block Design dialog before writing them into page CSS via a DOM sink, permitting stored cross-site scripting. An editor-level user could execute script in an administrator's session and escalate privileges. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 7.0 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:L/VI:H/VA:H/SC:N/SI:N/SA:N. Thanks Nguyen Manh Thuan for reporting.

## Affected Products

- Concrete CMS — Concrete CMS (5.0.0)

## References

- [CNA](https://documentation.concretecms.org/developers/introduction/version-history/953-release-notes)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.31%
- **EPSS Percentile:** 23.7

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-17._