CVE-2025-63842 in Repetico
Summary
by MITRE • 09/14/2026
A Cross-Site Scripting (XSS) vulnerability in the web backend for the Repetico app 1.9.7.31 for Android allows a remote authenticated user to execute arbitrary JavaScript code in the app's context via crafted input in the multiple-choice question text field.
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Analysis
by VulDB Data Team • 09/14/2026
The identified security flaw represents a classic instance of Cross-Site Scripting, specifically categorized under CWE-79 within the Common Weakness Enumeration framework. This vulnerability exists within the web backend infrastructure supporting Repetico app version 1.9.7.31 for Android devices. The core technical deficiency lies in the insufficient sanitization and validation of user-supplied input data before it is processed or rendered by the application's interface. Specifically, the multiple-choice question text field fails to properly encode special characters that have meaning in HTML and JavaScript contexts. When a remote authenticated user submits crafted input containing executable script tags or event handlers into this specific field, the backend accepts the payload without adequate filtering. Consequently, when other users view the content associated with these questions, their browsers interpret the injected code as legitimate part of the page structure rather than data, leading to the execution of arbitrary JavaScript within the security context of the application's domain.
From an operational perspective, this vulnerability poses significant risks beyond simple defacement or visual manipulation. Because the malicious script executes in the same origin as the authenticated user session, it can access sensitive cookies, local storage items, and other credentials stored by the browser for that specific domain. An attacker could leverage this capability to perform actions on behalf of the victim without their knowledge or consent, a technique often referred to as Cross-Site Request Forgery augmentation via script injection. Furthermore, the attacker might be able to steal session tokens, effectively hijacking user accounts and gaining unauthorized access to private data such as study progress, personal information, or any other sensitive content stored within the application's ecosystem. This aligns with several tactics in the MITRE ATT&CK framework, particularly T1059 which covers Command and Scripting Interpreter usage for lateral movement or persistence, although here it is primarily used for session hijacking and data exfiltration rather than system-level command execution.
The presence of this vulnerability indicates a gap in the application's input validation strategy, suggesting that developers may have relied on client-side checks alone or failed to implement robust server-side encoding mechanisms such as HTML entity encoding for all dynamic content rendered from user inputs. The fact that authentication is required prior to exploitation narrows the attack surface slightly compared to unauthenticated XSS flaws but does not mitigate the severity of potential data breaches among authenticated users who may include students, educators, and administrators with varying levels of privilege.
To remediate this issue, immediate action must be taken by the development team to implement strict output encoding on all user-supplied data before it is rendered in HTML contexts. This involves ensuring that special characters like ampersands, less-than signs, greater-than signs, quotes, and apostrophes are properly encoded using context-aware techniques appropriate for HTML body content. Additionally, implementing a Content Security Policy header can provide an additional layer of defense by restricting the sources from which scripts can be loaded or executed, thereby mitigating the impact even if some injection attempts succeed. Input validation should also be strengthened to reject any input containing script-like patterns at the server level before processing occurs. Regular security audits and penetration testing focusing on web application vulnerabilities are recommended to identify similar weaknesses in other fields across the platform.