CVE-2025-8265 is a vulnerability identified in version 2.0.0 of the 299Ko Content Management System (CMS), specifically within the file management component accessible at /admin/filemanager/view. The flaw allows an attacker to perform unrestricted file uploads remotely without requiring user interaction or authentication. This means that an attacker with network access to the CMS can upload arbitrary files, potentially including malicious scripts or executables, which can lead to further compromise of the affected system. The vulnerability is classified as medium severity with a CVSS 4.0 base score of 5.1, reflecting a network attack vector with low complexity and no user interaction, but requiring high privileges (PR:H). The impact on confidentiality, integrity, and availability is rated low, indicating that while exploitation is possible, the scope of damage may be limited or require additional conditions to escalate. The vendor has not responded to the disclosure, and no patches or mitigations have been published yet. Although no known exploits are currently observed in the wild, the public disclosure of the exploit code increases the risk of exploitation by threat actors. The vulnerability's unrestricted upload capability can be leveraged to deploy web shells, malware, or ransomware, potentially leading to data breaches, defacement, or service disruption.

For European organizations using 299Ko CMS version 2.0.0, this vulnerability poses a tangible risk of unauthorized system compromise. Since the flaw allows remote file uploads without authentication, attackers could gain a foothold in web servers hosting the CMS, leading to potential data exfiltration, website defacement, or pivoting to internal networks. The impact is particularly significant for organizations handling sensitive personal data under GDPR, as a breach could result in regulatory penalties and reputational damage. Additionally, critical infrastructure or public sector entities using this CMS might face service disruptions or targeted attacks. The medium severity rating suggests that while exploitation is feasible, the requirement for high privileges may limit the attack surface to administrators or users with elevated rights, somewhat reducing the risk for general internet-facing instances. However, if privilege escalation vulnerabilities coexist, the threat could escalate to critical levels. The lack of vendor response and absence of patches increase the urgency for organizations to implement compensating controls to mitigate potential exploitation.

Given the absence of official patches, European organizations should immediately audit their 299Ko CMS installations to identify version 2.0.0 deployments. Restrict access to the /admin/filemanager/view endpoint using network-level controls such as IP whitelisting or VPN access to limit exposure to trusted administrators only. Implement web application firewalls (WAFs) with rules to detect and block suspicious file upload patterns or unauthorized HTTP methods targeting the file manager. Conduct thorough logging and monitoring of file upload activities to detect anomalies promptly. Where possible, disable or restrict file upload functionality until a patch is available. Employ file integrity monitoring to detect unauthorized changes in web directories. Additionally, enforce the principle of least privilege for CMS users to minimize the number of accounts with high privileges. Organizations should also prepare incident response plans specific to web shell detection and removal. Finally, maintain regular backups of CMS data and configurations to enable rapid recovery if compromise occurs.