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,… (CVE-2026-18119)
Concrete CMS versions below 9.5.3 contain a stored cross-site scripting (XSS) vulnerability due to improper sanitization of custom style values in the Block Design dialog. This flaw allows an editor-level user to inject script code that executes in an context of an administrator's session, potentially enabling privilege escalation. The vulnerability has a high severity rating with a CVSS v4.0 score of 7.0.
AI Analysis
Technical Summary
Concrete CMS versions prior to 9.5.3 do not sanitize custom style values entered in the Block Design dialog before embedding them into page CSS via a DOM sink. This lack of sanitization permits stored cross-site scripting (CWE-79), allowing an attacker with editor-level privileges to execute arbitrary scripts in an administrator's session. The vulnerability has a CVSS v4.0 base score of 7.0 (AV:N/AC:L/PR:H/UI:P/VC:L/VI:H/VA:H/SC:N/SI:N/SA:N), indicating network attack vector, low attack complexity, and high impact on confidentiality, integrity, and availability.
Potential Impact
An attacker with editor-level access can exploit this vulnerability to execute arbitrary scripts in the context of an administrator's session. This can lead to privilege escalation and unauthorized actions performed with administrator privileges. The vulnerability affects confidentiality, integrity, and availability of the affected system.
Mitigation Recommendations
A fix is available in Concrete CMS version 9.5.3 and later. Users should upgrade to version 9.5.3 or newer to remediate this vulnerability. No additional mitigations are specified.
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,… (CVE-2026-18119)
Description
Concrete CMS versions below 9.5.3 contain a stored cross-site scripting (XSS) vulnerability due to improper sanitization of custom style values in the Block Design dialog. This flaw allows an editor-level user to inject script code that executes in an context of an administrator's session, potentially enabling privilege escalation. The vulnerability has a high severity rating with a CVSS v4.0 score of 7.0.
CVSS v4.0
Affected software
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Concrete CMS versions prior to 9.5.3 do not sanitize custom style values entered in the Block Design dialog before embedding them into page CSS via a DOM sink. This lack of sanitization permits stored cross-site scripting (CWE-79), allowing an attacker with editor-level privileges to execute arbitrary scripts in an administrator's session. The vulnerability has a CVSS v4.0 base score of 7.0 (AV:N/AC:L/PR:H/UI:P/VC:L/VI:H/VA:H/SC:N/SI:N/SA:N), indicating network attack vector, low attack complexity, and high impact on confidentiality, integrity, and availability.
Potential Impact
An attacker with editor-level access can exploit this vulnerability to execute arbitrary scripts in the context of an administrator's session. This can lead to privilege escalation and unauthorized actions performed with administrator privileges. The vulnerability affects confidentiality, integrity, and availability of the affected system.
Mitigation Recommendations
A fix is available in Concrete CMS version 9.5.3 and later. Users should upgrade to version 9.5.3 or newer to remediate this vulnerability. No additional mitigations are specified.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-fjhh-g9g9-wm99
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-18119"]
- Database Specific Severity
- HIGH
- Cvss Version
- 4.0
Threat ID: 6aa8a1c755bf5e2cf5f3e8da
Added to database: 09/15/2026, 01:39:19 UTC
Last enriched: 09/15/2026, 01:58:39 UTC
Last updated: 09/15/2026, 01:58:39 UTC
Views: 2
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