CVE-2026-1107 is a vulnerability identified in EyouCMS, a content management system, specifically affecting versions 1.7.0, 1.7.1, and 5.0. The vulnerability resides in the Member Avatar Handler component within the check_userinfo function of the Diyajax.php file. By manipulating the 'viewfile' parameter, an attacker can perform an unrestricted file upload remotely without requiring authentication or user interaction. This allows the attacker to upload arbitrary files, potentially leading to remote code execution, website defacement, data theft, or further compromise of the underlying server. The vulnerability has a CVSS 4.0 base score of 5.3, indicating medium severity, with characteristics including network attack vector, low attack complexity, no privileges required, and no user interaction needed. The scope is limited to the vulnerable EyouCMS installations, and the impact on confidentiality, integrity, and availability is low to limited but non-negligible. The vendor has not issued any patches or responses despite early notification, and public exploit code is available, increasing the risk of exploitation. No active exploitation has been reported yet, but the presence of public exploits necessitates proactive defense measures. This vulnerability highlights the risks of insufficient input validation and access control in web application components handling file uploads.

For European organizations using EyouCMS, this vulnerability poses a significant risk of unauthorized access and control over web servers. Successful exploitation can lead to arbitrary file uploads, enabling attackers to deploy web shells, execute malicious code, or pivot within the network. This can result in data breaches, defacement of public-facing websites, disruption of services, and potential lateral movement to critical internal systems. Given the lack of vendor response and patches, organizations face prolonged exposure. The impact is particularly critical for entities hosting sensitive data or providing essential services via EyouCMS-powered websites. Additionally, regulatory implications under GDPR may arise if personal data is compromised. The medium severity rating suggests a moderate but actionable risk, especially in sectors such as government, finance, healthcare, and media where website integrity and availability are paramount. The public availability of exploit code lowers the barrier for attackers, increasing the likelihood of opportunistic attacks targeting vulnerable European organizations.

1. Immediately restrict access to the Diyajax.php endpoint, especially the check_userinfo function, using web application firewalls (WAFs) or network-level controls to block unauthorized requests. 2. Implement strict server-side validation and sanitization of all file upload parameters, particularly the 'viewfile' argument, to prevent arbitrary file uploads. 3. Employ file type and content verification to ensure only legitimate avatar images are accepted, rejecting executable or script files. 4. Monitor web server logs and application logs for unusual upload attempts or access patterns targeting the vulnerable component. 5. Isolate EyouCMS instances in segmented network zones to limit potential lateral movement if compromise occurs. 6. Regularly back up website data and configurations to enable rapid recovery in case of an incident. 7. Engage in active threat hunting for indicators of compromise related to this vulnerability. 8. Consider deploying runtime application self-protection (RASP) solutions to detect and block exploitation attempts in real time. 9. Stay alert for vendor updates or community patches and apply them promptly once available. 10. If feasible, migrate to alternative CMS platforms with better security track records until this vulnerability is resolved.