CVE-2023-53892 affects Blackcat CMS version 1.4 and involves an unrestricted file upload vulnerability within the jQuery plugin manager component. Authenticated administrators can upload a zip file containing a malicious PHP shell script disguised as a plugin. The vulnerability arises because the system does not properly restrict or sanitize the file types allowed for upload, enabling dangerous file types such as PHP scripts to be uploaded and stored on the server. Once uploaded, the attacker can invoke the malicious PHP file by accessing it directly and passing a 'code' parameter, which triggers execution of arbitrary system commands on the underlying server. This leads to remote code execution (RCE) with the privileges of the web server process, which can result in full system compromise. The CVSS 4.0 score is 8.6 (high), reflecting network attack vector, low attack complexity, no user interaction, and high impact on confidentiality, integrity, and availability. The vulnerability requires authenticated administrator access, which limits exposure to insiders or compromised admin credentials but remains critical due to the severity of impact. No patches or exploit code are currently publicly available, but the vulnerability is published and should be addressed promptly.

For European organizations, exploitation of this vulnerability could lead to complete takeover of web servers hosting Blackcat CMS 1.4, resulting in data breaches, defacement, ransomware deployment, or lateral movement within internal networks. Confidential information managed by the CMS could be exposed or altered, damaging organizational reputation and violating data protection regulations such as GDPR. Availability of critical web services could be disrupted, impacting business operations. Since the vulnerability requires administrator credentials, the risk is heightened if credential theft or insider threats exist. Organizations in sectors with high reliance on web content management systems—such as government, education, healthcare, and media—face increased risk. The lack of known exploits in the wild provides a window for proactive mitigation, but the potential impact remains severe if exploited.

1. Immediately upgrade Blackcat CMS to a version that patches this vulnerability once available. If no patch exists, consider disabling the jQuery plugin manager or restricting its use to trusted personnel only. 2. Enforce strict access controls and multi-factor authentication (MFA) for administrator accounts to reduce the risk of credential compromise. 3. Implement web application firewalls (WAF) with custom rules to detect and block suspicious file uploads and access patterns related to plugin uploads and PHP file execution. 4. Conduct regular audits of uploaded files on the server to identify and remove unauthorized PHP scripts or suspicious files. 5. Monitor server logs for unusual access to plugin directories or execution of PHP files with unexpected parameters. 6. Employ network segmentation to limit the impact of a compromised CMS server on the broader organizational network. 7. Educate administrators on secure upload practices and the risks of uploading untrusted plugins or files. 8. Consider deploying runtime application self-protection (RASP) tools to detect and block exploitation attempts in real time.