CVE-2025-49054 is a high-severity reflected Cross-Site Scripting (XSS) vulnerability identified in the mrdenny Time Sheets application, specifically affecting versions up to 2.1.3. This vulnerability arises from improper neutralization of user-supplied input during web page generation, classified under CWE-79. Reflected XSS occurs when malicious scripts injected via crafted URLs or input fields are immediately reflected back in the HTTP response without proper sanitization or encoding, allowing attackers to execute arbitrary JavaScript in the context of the victim's browser. The CVSS v3.1 base score of 7.1 reflects a network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), but requiring user interaction (UI:R). The scope is changed (S:C), indicating that exploitation can affect resources beyond the vulnerable component, with impacts on confidentiality, integrity, and availability rated as low but present (C:L/I:L/A:L). Although no public exploits are currently known, the vulnerability poses a significant risk because it can be exploited remotely without authentication, potentially leading to session hijacking, credential theft, or unauthorized actions on behalf of the user. The lack of available patches at the time of publication increases exposure. The vulnerability affects the mrdenny Time Sheets product, a time tracking and management tool, which is likely used in various organizational environments to monitor employee work hours and project time allocations. Attackers exploiting this vulnerability could leverage social engineering to trick users into clicking malicious links, resulting in script execution within the user's browser session. This could lead to theft of sensitive information or manipulation of time sheet data, undermining data integrity and confidentiality.

For European organizations, the impact of this vulnerability can be significant, especially for those relying on mrdenny Time Sheets for workforce management and billing accuracy. Exploitation could lead to unauthorized disclosure of sensitive employee or project data, manipulation of time records affecting payroll and compliance, and potential lateral movement within the corporate network if session tokens or credentials are stolen. Given the reflected nature of the XSS, phishing campaigns could be tailored to employees, increasing the risk of successful exploitation. This could result in financial losses, reputational damage, and regulatory non-compliance, particularly under GDPR, which mandates protection of personal data. The availability impact, while rated low, could still disrupt business operations if exploited at scale. Additionally, the change in scope indicates that the vulnerability could affect other components or services integrated with the Time Sheets application, amplifying the potential damage.

Organizations should implement immediate mitigations including: 1) Applying any available patches or updates from mrdenny as soon as they are released. 2) Employing Web Application Firewalls (WAFs) configured to detect and block reflected XSS attack patterns targeting the Time Sheets application. 3) Conducting input validation and output encoding on all user-supplied data within the application, particularly in URL parameters and form inputs, to neutralize malicious scripts. 4) Educating users about the risks of clicking on suspicious links, especially those purporting to be related to time tracking or HR functions. 5) Implementing Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in browsers. 6) Monitoring application logs and network traffic for unusual activity indicative of attempted exploitation. 7) Reviewing and restricting permissions and session management to minimize the impact of potential session hijacking. 8) Considering temporary disabling or restricting external access to the Time Sheets application if feasible until mitigations are in place. These steps go beyond generic advice by focusing on immediate protective controls and user awareness tailored to this specific vulnerability and product context.