CVE-2025-15375 is a deserialization vulnerability affecting EyouCMS, a content management system, in versions 1.7.0 through 1.7.7. The flaw exists in the unserialize function located in application/api/controller/Ajax.php within the arcpagelist handler component. Specifically, the vulnerability arises from unsafe deserialization of user-controlled input passed via the 'attstr' argument. Deserialization vulnerabilities occur when untrusted data is converted back into objects or data structures without proper validation or sanitization, potentially allowing attackers to inject malicious objects or payloads. This can lead to remote code execution, privilege escalation, or other impacts depending on the deserialized object's behavior. The attack vector is remote network access, requiring no user interaction and only low privileges, making exploitation relatively straightforward. The CVSS 4.0 score is 5.3 (medium), reflecting moderate impact and ease of exploitation. The vendor has acknowledged the vulnerability and is preparing a patch in version 1.7.8. While no active exploitation has been confirmed, published exploits increase the risk of imminent attacks. Organizations using affected EyouCMS versions should urgently assess exposure and apply updates once available. The vulnerability does not require authentication, increasing its risk profile, but the impact is somewhat limited by the scope and complexity of exploitation. This vulnerability highlights the risks of unsafe deserialization in web applications and the importance of secure coding practices and timely patching.

For European organizations using EyouCMS, this vulnerability poses a moderate risk of remote compromise without authentication or user interaction. Successful exploitation could lead to unauthorized code execution, data manipulation, or service disruption, impacting confidentiality, integrity, and availability of web services. Organizations hosting sensitive or critical data on EyouCMS platforms may face data breaches or operational outages. The medium severity score suggests the impact is significant but not catastrophic, though combined with other vulnerabilities or poor network segmentation, the risk could escalate. The presence of published exploits increases the likelihood of attacks targeting unpatched systems. European entities in sectors such as government, finance, healthcare, or media using EyouCMS could be targeted to gain footholds or disrupt services. The vulnerability could also be leveraged as a pivot point for lateral movement within networks. Given the remote attack vector and no need for user interaction, the threat is accessible to a wide range of attackers, including automated scanning and exploitation tools. Overall, the vulnerability represents a tangible risk that requires prompt mitigation to prevent compromise.

European organizations should immediately inventory their EyouCMS deployments to identify affected versions (1.7.0 through 1.7.7). They should plan to upgrade to version 1.7.8 or later as soon as the patch is released by the vendor. Until patching is possible, organizations can implement web application firewall (WAF) rules to detect and block suspicious requests containing serialized payloads targeting the 'attstr' parameter. Input validation and sanitization should be enhanced to reject unexpected or malformed serialized data. Network segmentation should isolate CMS servers from critical internal systems to limit potential lateral movement. Monitoring and logging should be increased around the vulnerable endpoint to detect exploitation attempts. Restricting access to the API controller to trusted IPs or via VPN can reduce exposure. Security teams should review and harden PHP unserialize usage in custom code if applicable. Regular vulnerability scanning and penetration testing should verify remediation effectiveness. Finally, organizations should educate developers on secure deserialization practices to prevent similar issues in the future.