CVE-2026-24010 is a critical vulnerability identified in horilla, an open-source Human Resource Management System, affecting versions prior to 1.5.0. The vulnerability stems from improper neutralization of special elements in output used by downstream components (CWE-74), specifically in the file upload functionality. Authenticated users can upload malicious HTML files disguised as profile pictures. These files can host phishing pages that mimic the legitimate login interface, displaying a 'Session Expired' message to trick users into re-entering their credentials. When victims access the URL of the uploaded malicious file, their credentials are captured and sent to the attacker’s server, enabling account takeover. This attack vector leverages social engineering combined with the technical flaw in input validation and output encoding. The vulnerability does not require user interaction beyond visiting the malicious URL, and no additional privileges beyond authentication are needed to exploit it. The CVSS v3.0 score of 8.8 reflects high impact on confidentiality, integrity, and availability, with low attack complexity and no user interaction required. Although no known exploits are currently reported in the wild, the vulnerability poses a significant risk due to the sensitive nature of HR data and potential for lateral movement within organizations. The issue is addressed in horilla version 1.5.0, which properly sanitizes uploaded files and restricts allowed file types to prevent HTML or script uploads.

For European organizations, this vulnerability poses a substantial threat to the security of HR systems, which often contain sensitive personal and employment data. Successful exploitation can lead to credential theft and account takeover, potentially allowing attackers to access confidential employee records, manipulate HR workflows, or escalate privileges within the network. The phishing aspect increases the risk of widespread credential compromise beyond the initial victim, potentially affecting multiple users. This can result in regulatory non-compliance under GDPR due to data breaches involving personal information, leading to legal and financial penalties. The availability of HR services may also be disrupted if attackers manipulate or lock accounts. Given the critical role of HR systems in organizational operations, the impact extends to operational disruption and reputational damage. European organizations using horilla or similar open-source HRMS platforms are particularly vulnerable if they have not applied the patch or implemented compensating controls.

To mitigate this vulnerability, European organizations should immediately upgrade horilla installations to version 1.5.0 or later, where the issue is patched. Until upgrade is possible, restrict file upload functionality to disallow HTML, script, or other executable content types, allowing only safe image formats such as JPEG or PNG. Implement strict server-side validation and sanitization of uploaded files to prevent malicious content. Employ Content Security Policy (CSP) headers to limit the execution of unauthorized scripts. Monitor file upload directories for suspicious files and URLs. Educate users about phishing risks and encourage verification of URLs before entering credentials. Implement multi-factor authentication (MFA) to reduce the impact of credential theft. Regularly audit user permissions to limit authenticated users' ability to upload files if possible. Finally, conduct penetration testing and code reviews focusing on input validation and output encoding to prevent similar vulnerabilities.