Vulnerability · Published Sep 15, 2026 · Assigned by ConcreteCMS
CVE-2026-81897Concrete CMS below version 9.5.3 is vulnerable to Stored XSS via Express form Text control save_control
High 7.7
In plain English
A high-severity cross-site request forgery in Concrete CMS from Concrete CMS. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 6% of all known vulnerabilities).
Official description
In Concrete CMS below CMS 9.5.3, the save_control action in the Express entities forms dashboard controller did not validate the anti-CSRF token. By causing an authenticated administrator to submit a forged cross-site request, a remote attacker without credentials could write attacker-controlled headline and body values to an existing Express form Text control. Those values were emitted without output encoding by the Express form Text element, so the injected markup executed as persistent JavaScript for any administrator who later opened the affected entry, resulting in stored cross-site scripting. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 7.7 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N. Thanks Yonatan Drori from Tenzai for reporting.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Concrete CMS | Concrete CMS | 5.0.0 – through 9.5.2 |
Weakness: CWE-352, CWE-79 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N