CVE-2026-59667 in Repasat
Summary
by MITRE • 10/02/2026
Cross-Site Scripting vulnerability in the Repasat application. Successful exploitation of this vulnerability could allow an attacker to trick a user into executing arbitrary code in the victim’s browser. The “nomTamano” parameter is affected – endpoint “/es/companysizemployees/update”.
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Analysis
by VulDB Data Team • 10/02/2026
The identified Cross-Site Scripting (XSS) flaw within the Repasat application represents a significant security risk, specifically located at the /es/companysizemployees/update endpoint. This vulnerability arises from inadequate input validation and sanitization mechanisms applied to the nomTamano parameter. When user-supplied data is processed by this specific function without proper encoding or filtering, it allows malicious scripts to be injected into the application's response stream. The core technical failure lies in the server-side handling of this parameter, where reflected content is rendered directly into the HTML context without neutralizing special characters that have meaning in JavaScript execution environments. This lack of robust output encoding creates a direct pathway for an attacker to inject executable client-side code, which will then be interpreted and run by the victim's web browser as part of the legitimate application page.
From an operational perspective, successful exploitation enables an attacker to execute arbitrary scripts within the security context of the affected website. This capability allows for severe consequences including session hijacking, where attackers can steal authentication cookies or tokens to impersonate valid users. It also facilitates credential harvesting through deceptive login forms that mimic authentic interfaces, as well as keylogging capabilities that capture sensitive data entered by victims. Furthermore, this vulnerability can be leveraged to deface the application interface or redirect users to malicious external sites designed for phishing attacks. The impact is compounded if the application handles sensitive corporate data, as the breach of user trust and potential exposure of confidential information could lead to significant reputational damage and regulatory non-compliance under standards such as GDPR or HIPAA depending on the industry sector.
In terms of classification frameworks, this vulnerability aligns with CWE-79: Improper Neutralization of Input During Web Page Generation commonly known as Cross-site Scripting. Specifically, it falls under the reflected variant where malicious input is immediately returned to the user without being stored in a database or persistent storage. From an offensive security perspective, such exploitation techniques are documented in MITRE ATT&CK framework under T1059: Command and Scripting Interpreter, particularly when scripts are used for reconnaissance or lateral movement within a compromised environment. Understanding these classifications helps in mapping the vulnerability to broader threat models and prioritizing remediation efforts based on industry-standard risk assessments.
To mitigate this vulnerability, developers must implement strict input validation that rejects any non-whitelisted characters in the nomTamano parameter before processing. More critically, output encoding must be applied consistently across all contexts where user data is rendered into HTML, JavaScript, or CSS. This involves using context-aware escaping functions provided by modern web frameworks to ensure special characters are converted into their safe entity equivalents. Additionally, implementing a Content Security Policy (CSP) header can provide an additional layer of defense by restricting the sources from which scripts can be loaded and executed, thereby mitigating the impact even if injection occurs. Regular security testing using both static application security testing tools and dynamic analysis should be integrated into the development lifecycle to detect such flaws early before deployment to production environments.