CVE-2026-3244 in Concrete
Summary
by MITRE • 03/04/2026
In Concrete CMS below version 9.4.8, A stored cross-site scripting (XSS) vulnerability exists in the search block where page names and content are rendered without proper HTML encoding in search results. This allows authenticated, rogue administrators to inject malicious JavaScript through page names that executes when users search for and view those pages in search results. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 4.8 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks zolpak for reporting
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Analysis
by VulDB Data Team • 03/06/2026
The vulnerability identified as CVE-2026-3244 represents a critical stored cross-site scripting flaw within Concrete CMS versions prior to 9.4.8. This security weakness specifically affects the search block functionality where user-generated content including page names and content are displayed in search results without adequate HTML encoding mechanisms. The flaw enables authenticated attackers with administrator privileges to inject malicious JavaScript code into page names, which then executes when other users perform searches and view the affected search results. This creates a persistent threat vector that can compromise user sessions and potentially lead to broader system exploitation.
The technical implementation of this vulnerability stems from insufficient input sanitization and output encoding within the search block component of Concrete CMS. When administrators create or modify pages with malicious payloads in their names, these inputs are stored in the database without proper HTML escaping or sanitization. During subsequent search operations, the system retrieves these stored values and renders them directly in the search result interface without appropriate encoding, allowing the injected JavaScript to execute in the context of other users' browsers. This stored XSS vulnerability operates at the application layer and specifically targets the content rendering pipeline of the CMS search functionality.
The operational impact of this vulnerability extends beyond simple script execution, as it enables authenticated attackers with administrator privileges to manipulate search results and potentially escalate their privileges within the system. The CVSS v4.0 score of 4.8 indicates a moderate severity threat with a vector showing network accessibility, low attack complexity, no user interaction requirement, and high privilege requirements. The vulnerability requires an attacker to already possess administrative credentials, but once compromised, it allows for persistent malicious activities including session hijacking, data exfiltration, and potential lateral movement within the CMS environment. This threat model aligns with CWE-79 which categorizes cross-site scripting vulnerabilities and supports the ATT&CK framework's T1566 technique for initial access through malicious content.
Mitigation strategies for this vulnerability should focus on immediate patching of Concrete CMS installations to version 9.4.8 or later, which includes proper HTML encoding fixes for search results. Organizations should implement comprehensive input validation and output encoding mechanisms throughout their CMS environments, particularly for user-generated content that appears in search results. Security teams should conduct thorough audits of all CMS components that handle user input, ensuring that proper sanitization techniques are applied before any content is rendered to end users. Additionally, implementing web application firewalls and content security policies can provide additional defense-in-depth layers to detect and prevent malicious script injection attempts in search functionality. Regular security assessments and penetration testing should be conducted to identify similar encoding vulnerabilities in other CMS components that may present similar attack surfaces.