CVE-2025-2967 in ConcreteCMS
Summary
by MITRE • 03/31/2025
A vulnerability was found in ConcreteCMS up to 9.3.9. It has been classified as problematic. This affects the function Save of the component HTML Block Handler. The manipulation of the argument content leads to HTML injection. It is possible to initiate the attack remotely. The exploit has been disclosed to the public and may be used. The vendor was contacted early about this disclosure but did not respond in any way.
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Analysis
by VulDB Data Team • 03/31/2025
The vulnerability identified as CVE-2025-2967 represents a critical HTML injection flaw within ConcreteCMS version 9.3.9 and earlier, specifically affecting the HTML Block Handler's Save function. This issue falls under the category of input validation failures and is classified as a CWE-79 - Cross-Site Scripting (XSS) vulnerability, which allows attackers to inject malicious HTML content into web applications. The vulnerability exists in the content parameter handling of the HTML Block component, where user-supplied input is not properly sanitized before being stored and rendered within the CMS interface.
The technical exploitation of this vulnerability occurs when an attacker manipulates the content argument passed to the Save function of the HTML Block Handler, enabling the injection of malicious HTML code that can be executed in the context of other users' browsers. This remote code execution capability stems from the lack of proper input filtering and output encoding mechanisms within the CMS's content handling pipeline. The flaw allows attackers to inject script tags, malicious JavaScript, or other HTML content that persists in the database and executes whenever the affected content is rendered to users.
The operational impact of this vulnerability extends beyond simple XSS attacks, as it can enable more sophisticated exploitation techniques including session hijacking, credential theft, and privilege escalation within the CMS environment. Attackers can leverage this vulnerability to create persistent backdoors, manipulate user sessions, or redirect users to malicious websites. The fact that this vulnerability has been publicly disclosed and is known to be exploitable means that it represents an active threat in the wild, with potential for widespread compromise of ConcreteCMS installations.
Organizations running affected ConcreteCMS versions should immediately implement mitigations including input sanitization, output encoding, and proper content validation. The recommended approach involves implementing comprehensive input filtering that removes or encodes potentially dangerous HTML characters, enforcing strict content security policies, and ensuring that all user-supplied content is properly escaped before storage and rendering. Additionally, organizations should consider implementing web application firewalls, regular security monitoring, and immediate patching procedures to address this vulnerability. The lack of vendor response to early disclosure attempts underscores the importance of proactive security measures and community-driven vulnerability management, aligning with ATT&CK technique T1190 - Exploit Public-Facing Application to establish persistent access through vulnerable web applications.