CVE-2026-59665 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 “nomMotivo” parameter is affected – endpoint “/es/lostmotives/store”.
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Analysis
by VulDB Data Team • 10/02/2026
The identified security flaw represents a classic Cross-Site Scripting (XSS) vulnerability within the Repasat web application, specifically targeting the input handling mechanisms of the /es/lostmotives/store endpoint. This type of vulnerability arises when an application accepts untrusted data and includes it in its output to a web browser without proper validation or encoding. In this specific instance, the nomMotivo parameter serves as the injection point for malicious scripts. The presence of this flaw indicates that the server-side processing logic fails to adequately sanitize user-supplied input before rendering it within the context of an HTML response. This lack of rigorous input validation allows attackers to inject client-side code that is subsequently executed by the victim's web browser, treating the injected content as legitimate script from the trusted domain hosting Repasat.
From a technical perspective, this vulnerability falls under CWE-79, which classifies Improper Neutralization of Input During Web Page Generation commonly known as Cross-site Scripting. The operational impact is significant because successful exploitation enables an attacker to execute arbitrary JavaScript in the context of the victim's session. This capability allows for a wide range of malicious activities beyond simple defacement or phishing pages. An attacker can steal sensitive information such as session cookies, authentication tokens, and personally identifiable data stored within local storage or accessed via DOM manipulation. Furthermore, the vulnerability facilitates account takeover scenarios where the attacker hijacks the active session of an authenticated user, potentially gaining unauthorized access to administrative functions or modifying application state on behalf of the victim.
The attack vector for this specific endpoint suggests that the nomMotivo field is likely used in a dynamic part of the page generation process without sufficient context-aware encoding. When a user submits data through the /es/lostmotives/store interface, if the server reflects this input back into the HTML structure or stores it for later retrieval and display without proper escaping, any script tags or event handlers embedded within that payload will be executed by the browser. This is particularly dangerous in single-page applications or dynamic forms where data flows frequently between client and server. The lack of output encoding means that special characters like angle brackets, quotes, and ampersands are not converted to their HTML entity equivalents, thereby preserving the executable nature of any injected script fragments.
Mitigation strategies must focus on both input validation and output encoding as primary defense layers. Developers should implement strict allow-list based input validation for the nomMotivo parameter, ensuring that only expected character sets such as alphanumeric characters or specific punctuation are accepted. More critically, all dynamic content rendered in HTML contexts must be properly encoded using context-specific techniques. For example, if the data is inserted into an HTML body element, it should undergo HTML entity encoding to prevent script execution. Additionally, implementing Content Security Policy headers can provide a robust defense-in-depth measure by restricting the sources from which scripts are allowed to load and execute, thereby mitigating the impact even if XSS vulnerabilities persist in the codebase.
From a threat intelligence perspective, this vulnerability aligns with MITRE ATT&CK technique T1059.007, JavaScript, which describes how attackers use client-side scripting languages like JavaScript to perform actions on behalf of users or within their environment. The exploitation chain typically involves crafting a malicious URL containing the injected script in the nomMotivo parameter and social engineering a victim into visiting that link while authenticated with Repasat. Once visited, the browser parses the response, executes the payload, and allows the attacker's code to interact with the Document Object Model of the application page. This interaction can be used to exfiltrate data via HTTP requests to an external server controlled by the attacker or to perform actions within the application that require higher privileges than those held by the victim user.
To further harden the application, it is recommended to adopt a defense-in-depth approach that includes using modern web frameworks with built-in XSS protection features such as automatic context-aware escaping. Developers should also consider implementing HttpOnly flags on session cookies to prevent JavaScript access to sensitive cookie data, thereby reducing the effectiveness of session hijacking attacks derived from this vulnerability. Regular security testing including dynamic application security scanning and manual penetration testing focused on input validation logic is essential to identify similar flaws across other parameters and endpoints within the Repasat ecosystem before they can be exploited in production environments.