CVE-2026-1107 is a vulnerability identified in EyouCMS versions 1.7.0, 1.7.1, and 5.0, specifically in the Member Avatar Handler component's check_userinfo function located in the Diyajax.php file. The flaw stems from insufficient validation of the 'viewfile' parameter, which can be manipulated remotely to perform unrestricted file uploads. This means an attacker can upload arbitrary files, including potentially malicious scripts, without requiring authentication or user interaction. The vulnerability is exploitable over the network (AV:N) with low attack complexity (AC:L) and no privileges required (PR:L indicates limited privileges but effectively no authentication needed for exploitation). The impact on confidentiality, integrity, and availability is low to limited individually but combined can lead to significant compromise such as remote code execution or defacement. The vendor was notified early but has not issued a patch or response, and the exploit code has been publicly released, increasing the urgency for mitigation. No known active exploitation has been reported yet. The CVSS 4.0 base score is 5.3, categorizing it as medium severity. The vulnerability does not require user interaction and affects the web application layer, making it a critical concern for web servers running EyouCMS. The lack of vendor response necessitates that organizations implement their own mitigations and monitoring to reduce risk.

For European organizations, the unrestricted file upload vulnerability in EyouCMS could lead to unauthorized remote code execution, website defacement, data leakage, or pivoting within internal networks. Organizations relying on EyouCMS for public-facing websites or intranet portals are particularly vulnerable, as attackers can upload web shells or malware to gain persistent access. This could disrupt business operations, damage reputation, and lead to regulatory non-compliance under GDPR if personal data is compromised. The medium severity score reflects that while exploitation is straightforward and remote, the impact depends on the attacker's payload and the organization's security posture. Given the lack of vendor patching, European entities must be vigilant, as attackers may target these systems opportunistically. The potential for lateral movement and further compromise increases risk in interconnected environments common in European enterprises. Additionally, sectors such as government, education, and SMEs using EyouCMS may face heightened exposure due to limited security resources.

Since no official patch is available, European organizations should immediately implement strict input validation on the 'viewfile' parameter to prevent arbitrary file uploads. Employ web application firewalls (WAFs) with custom rules to block suspicious upload attempts targeting Diyajax.php and the Member Avatar Handler. Restrict allowed file types and enforce file size limits on uploads. Disable or restrict the vulnerable functionality if it is not critical to operations. Conduct regular file integrity monitoring on upload directories to detect unauthorized changes. Apply network segmentation to isolate web servers running EyouCMS from sensitive internal systems. Monitor logs for unusual activity related to file uploads and access to Diyajax.php. Educate administrators on the risk and ensure timely incident response readiness. Consider migrating to alternative CMS platforms if vendor support remains absent. Finally, maintain up-to-date backups to enable recovery in case of compromise.