CVE-2024-58295 is a vulnerability classified under CWE-434 (Unrestricted Upload of File with Dangerous Type) affecting ElkArte Forum version 1.1.9. The flaw enables authenticated administrators to upload arbitrary files, including PHP scripts, through the theme installation feature. Specifically, the forum software fails to properly validate or restrict the types of files contained within the uploaded ZIP archive. An attacker with administrator credentials can craft a ZIP archive containing a malicious PHP file that, once uploaded and extracted into the theme directory, can be accessed via a web request to execute arbitrary system commands on the server. This results in remote code execution (RCE) with the privileges of the web server process. The CVSS 4.0 score of 8.6 reflects the high impact and ease of exploitation given the low attack complexity and no requirement for user interaction. However, the attack requires prior administrator authentication, which limits the attack surface to insiders or compromised admin accounts. No patches or exploit code are currently publicly available, but the vulnerability poses a critical risk to the confidentiality, integrity, and availability of affected systems. The lack of secure file upload validation and insufficient sanitization in the theme installation process are the root causes. This vulnerability could be leveraged to deploy web shells, pivot within the network, or exfiltrate sensitive data.

For European organizations using ElkArte Forum 1.1.9, this vulnerability presents a significant risk of full server compromise. Successful exploitation can lead to unauthorized access to sensitive data, disruption of forum services, and potential lateral movement within corporate networks. Given that the vulnerability requires administrator authentication, the primary risk vector is insider threats or credential compromise. However, many organizations may not have stringent controls on administrator access or may expose administrative interfaces to the internet, increasing risk. The ability to execute arbitrary code remotely can also facilitate deployment of ransomware or other malware, impacting business continuity. In sectors such as government, finance, or critical infrastructure where forums may be used for internal communications or customer engagement, the impact could extend to reputational damage and regulatory penalties under GDPR if personal data is compromised. The vulnerability’s high severity and ease of exploitation make it a priority for European entities to address promptly.

1. Immediately restrict access to the ElkArte Forum administrative interface using network-level controls such as VPNs or IP whitelisting to limit administrator login exposure. 2. Enforce strong, multi-factor authentication for all administrator accounts to reduce the risk of credential compromise. 3. Monitor and audit all theme installation activities and uploaded files for suspicious content or unexpected file types. 4. If possible, disable the theme installation feature temporarily until a patch or update is available. 5. Implement web application firewall (WAF) rules to detect and block attempts to upload or access PHP files in theme directories. 6. Run the ElkArte Forum application in a sandboxed or containerized environment with minimal privileges to limit the impact of potential code execution. 7. Regularly back up forum data and server configurations to enable rapid recovery in case of compromise. 8. Stay informed about vendor updates and apply patches as soon as they are released. 9. Conduct internal security awareness training for administrators to recognize phishing or social engineering attempts that could lead to credential theft. 10. Review and harden server configurations to prevent execution of unauthorized scripts in upload directories.