CVE-2025-34111 is a critical unauthenticated arbitrary file upload vulnerability affecting Tiki Wiki CMS Groupware version 15.1 and earlier. The vulnerability resides in the ELFinder component's default connector (connector.minimal.php), which is exposed at the path /vendor_extra/elfinder/. This component fails to enforce proper file type validation, allowing remote attackers to upload malicious files, including executable PHP scripts, without authentication. By crafting a specially designed POST request to the ELFinder interface, an attacker can upload and execute arbitrary PHP code on the web server hosting the vulnerable Tiki Wiki CMS Groupware instance. This leads to a complete compromise of the affected system, as the attacker can execute commands with the privileges of the web server process. The vulnerability is classified under CWE-434 (Unrestricted Upload of File with Dangerous Type), CWE-306 (Missing Authentication for Critical Function), and CWE-20 (Improper Input Validation). The CVSS 4.0 base score is 9.3 (critical), reflecting its network attack vector, no required privileges or user interaction, and high impact on confidentiality, integrity, and availability. No known public exploits have been reported yet, but the severity and ease of exploitation make it a significant threat. The vulnerability affects all versions up to 15.1, indicating a broad scope of potentially impacted deployments. Since the ELFinder connector is commonly used for file management within Tiki CMS, the exposure of this interface without authentication is a critical security oversight. Attackers leveraging this vulnerability can gain persistent remote code execution, enabling data theft, defacement, lateral movement, or establishment of backdoors.

For European organizations using Tiki Wiki CMS Groupware, this vulnerability poses a severe risk. Many public sector entities, educational institutions, and community organizations in Europe utilize open-source CMS platforms like Tiki for collaboration and content management. A successful exploit could lead to unauthorized access to sensitive data, disruption of services, and potential spread of malware within organizational networks. Given the unauthenticated nature of the exploit, attackers can target vulnerable systems remotely without prior access, increasing the likelihood of widespread exploitation. The impact extends to confidentiality breaches (exfiltration of sensitive documents), integrity violations (alteration or deletion of content), and availability disruptions (defacement or denial of service). Additionally, compromised systems could be leveraged as pivot points for further attacks against internal infrastructure or supply chain partners. The lack of authentication and input validation also means automated scanning and exploitation tools could be developed rapidly, increasing the threat to European organizations that have not patched or mitigated this vulnerability. The critical CVSS score underscores the urgency for European entities to address this issue promptly to avoid operational and reputational damage.

1. Immediate upgrade: Organizations should upgrade Tiki Wiki CMS Groupware to a version beyond 15.1 once an official patch addressing CVE-2025-34111 is released by the Tiki Software Community Association. 2. Temporary access restrictions: Until a patch is available, restrict access to the /vendor_extra/elfinder/ directory using web server configuration (e.g., IP whitelisting, authentication requirements, or disabling the ELFinder connector if not in use). 3. Web application firewall (WAF): Deploy and configure a WAF to detect and block suspicious POST requests targeting the ELFinder interface, especially those attempting to upload PHP or other executable files. 4. File upload validation: Implement additional server-side validation to restrict allowed file types and enforce strict content-type checks, preventing execution of uploaded scripts. 5. Monitoring and logging: Enable detailed logging of file upload activities and monitor for anomalous behavior or unexpected file creations within the web root. 6. Incident response readiness: Prepare to isolate and remediate compromised systems quickly, including forensic analysis and restoration from clean backups. 7. Network segmentation: Limit the web server’s access to internal resources to reduce potential lateral movement in case of compromise. 8. Disable unnecessary components: If ELFinder is not required, disable or remove it entirely to reduce the attack surface. These measures, combined with timely patching, will significantly reduce the risk posed by this vulnerability.