CVE-2026-5210 is a remote file inclusion (RFI) vulnerability identified in SourceCodester Leave Application System version 1.0. The vulnerability stems from insufficient validation of the 'page' parameter, which is manipulated by attackers to include arbitrary files on the web server. This can lead to unauthorized disclosure of sensitive files, code execution, or server compromise depending on the included content. The vulnerability requires no authentication or user interaction, making it straightforward to exploit remotely over the network. The CVSS 4.0 vector indicates network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), and partial impact on confidentiality, integrity, and availability (VC:L, VI:L, VA:L). Although no active exploitation in the wild has been reported, the availability of a public exploit increases the likelihood of attacks. The vulnerability affects only version 1.0 of the product, and no official patches have been linked yet. This type of vulnerability is critical in web applications as it can be leveraged to execute arbitrary code, access sensitive data, or disrupt service. The lack of scope change (S:N) means the impact is limited to the vulnerable component but can still be severe depending on the environment.

The potential impact of CVE-2026-5210 is significant for organizations using the SourceCodester Leave Application System 1.0. Successful exploitation can lead to unauthorized file inclusion, which may expose sensitive configuration files, source code, or credentials stored on the server. Attackers could also execute arbitrary code if they manage to include malicious scripts, potentially leading to full server compromise. This compromises confidentiality, integrity, and availability of the affected system and possibly the broader network if the compromised server is a pivot point. The vulnerability's remote and unauthenticated nature increases the attack surface and risk. Organizations relying on this system for employee leave management may face data breaches, operational disruption, and reputational damage. Additionally, the presence of a public exploit lowers the barrier for attackers, increasing the likelihood of exploitation attempts. Without mitigation, this vulnerability could be leveraged in targeted attacks or automated scanning campaigns.

To mitigate CVE-2026-5210, organizations should first seek official patches or updates from SourceCodester and apply them promptly once available. In the absence of patches, immediate steps include implementing strict input validation and sanitization on the 'page' parameter to prevent arbitrary file paths. Employ whitelisting techniques to allow only legitimate page names or paths. Configure the web server to disable dynamic file inclusion where possible and restrict file system permissions to limit accessible files. Use web application firewalls (WAFs) to detect and block suspicious requests attempting file inclusion attacks. Regularly audit and monitor server logs for unusual access patterns targeting the vulnerable parameter. Consider isolating the application environment to minimize impact if compromised. Educate developers on secure coding practices to prevent similar vulnerabilities in future releases. Finally, conduct penetration testing and vulnerability scanning to verify the effectiveness of mitigations.