CVE-2026-2666 is a vulnerability identified in mingSoft MCMS version 6.1.1, specifically in the Template Archive Handler component accessed via the /ms/file/uploadTemplate.do endpoint. The vulnerability arises from insufficient validation or restrictions on the 'File' argument, allowing an attacker to upload arbitrary files without proper controls. This unrestricted upload capability can be exploited remotely, enabling attackers to place malicious files on the server, potentially leading to code execution, defacement, or further compromise of the system. The CVSS 4.0 base score is 5.1 (medium), reflecting that exploitation requires high-level privileges (PR:H), no user interaction (UI:N), and no authentication bypass (AT:N). The impact on confidentiality, integrity, and availability is limited but present (VC:L, VI:L, VA:L). Although no known exploits are currently active in the wild, proof-of-concept code has been published, increasing the risk of exploitation. The vulnerability does not affect the scope beyond the vulnerable component and does not require user interaction, but the prerequisite of high privileges limits the attack surface to authenticated users with elevated rights. The lack of available patches at the time of publication necessitates immediate attention from administrators to implement compensating controls.

For European organizations, this vulnerability poses a moderate risk primarily to those using mingSoft MCMS 6.1.1 for content management and template handling. Successful exploitation could allow attackers to upload malicious files, potentially leading to unauthorized code execution, website defacement, or disruption of services. This could result in data integrity issues, service downtime, and reputational damage. Organizations in sectors such as government, finance, healthcare, and critical infrastructure that rely on mingSoft MCMS for web content management are particularly at risk. The requirement for high privilege access reduces the likelihood of widespread exploitation but highlights the importance of strict access controls and monitoring. If exploited, attackers could leverage the uploaded files to pivot within the network or establish persistence, increasing the overall threat to organizational cybersecurity posture.

1. Immediately restrict access to the /ms/file/uploadTemplate.do endpoint to only trusted administrators and monitor access logs for suspicious activity. 2. Enforce the principle of least privilege by reviewing and limiting user permissions, ensuring only necessary users have high-level privileges required to exploit this vulnerability. 3. Implement web application firewalls (WAFs) with rules to detect and block anomalous file upload attempts targeting this endpoint. 4. Conduct regular integrity checks on uploaded files and maintain strict file type and size validation policies. 5. Monitor system and application logs for unusual file upload activities or errors related to the Template Archive Handler. 6. Engage with mingSoft for official patches or updates and apply them promptly once available. 7. Consider isolating the MCMS environment or running it within a sandboxed environment to limit potential damage from exploitation. 8. Educate administrators about the risks of this vulnerability and the importance of secure credential management to prevent privilege escalation.