CVE-2025-11353 identifies a vulnerability in the code-projects Online Hotel Reservation System version 1.0, specifically in the /admin/addgalleryexec.php script. The vulnerability arises from insufficient validation of the 'image' parameter, allowing an attacker to upload arbitrary files without restrictions. This unrestricted file upload can be exploited remotely without user interaction, though it requires low-level privileges, likely meaning an attacker must have some form of authenticated access or leverage a low-privilege account. The lack of proper file type validation or sanitization enables attackers to upload malicious files such as web shells or scripts, which can then be executed on the server. This can lead to remote code execution, data theft, defacement, or further compromise of the affected system. The vulnerability has a CVSS 4.0 base score of 5.3, indicating medium severity, with the vector showing network attack vector, low attack complexity, no user interaction, and low privileges required. Although no patches are currently linked, the exploit code is publicly available, increasing the urgency for mitigation. The vulnerability affects only version 1.0 of the product, which may limit exposure but still poses a significant risk to organizations using this system in production environments.

For European organizations, particularly those in the hospitality and tourism sectors using the affected Online Hotel Reservation System, this vulnerability could lead to unauthorized access and control over web servers hosting the application. Potential impacts include data breaches involving customer personal and payment information, defacement of websites damaging brand reputation, and disruption of reservation services causing operational and financial losses. Attackers could leverage uploaded malicious files to pivot within internal networks, increasing the scope of compromise. Given the public availability of exploit code, the risk of automated attacks and widespread exploitation is elevated. Organizations failing to mitigate this vulnerability may face regulatory penalties under GDPR if customer data is compromised. The medium severity rating reflects that while the vulnerability requires some level of access, the consequences of exploitation can be significant, especially in environments with weak internal controls or exposed administrative interfaces.

Organizations should immediately implement strict server-side validation of all file uploads, ensuring only allowed file types (e.g., images with specific MIME types and extensions) are accepted. Employ content inspection techniques to detect and block executable or script files disguised as images. Restrict upload directories with appropriate permissions to prevent execution of uploaded files, such as placing them outside the web root or disabling script execution in upload folders via web server configuration. Implement multi-factor authentication and least privilege principles for administrative access to reduce the risk of unauthorized access. Regularly monitor logs for suspicious upload activity and anomalous file creations. If possible, upgrade to a patched version of the software once available or apply vendor-provided fixes. Conduct penetration testing focused on file upload functionalities to verify the effectiveness of mitigations. Additionally, network segmentation can limit the impact if a compromise occurs.