CVE-2025-48051 in Lila
Summary
by MITRE • 05/15/2025
powertip.ts in Lila (for Lichess) before ab0beaf allows XSS in some applications because of an innerHTML usage pattern in which text is extracted from a DOM node and interpreted as HTML.
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Analysis
by VulDB Data Team • 06/12/2025
The vulnerability identified as CVE-2025-48051 affects the powertip.ts component within the Lila framework used by Lichess, a popular online chess platform. This issue represents a classic cross-site scripting vulnerability that emerges from improper handling of user-provided content within the application's tooltip functionality. The vulnerability manifests when text content is extracted from a DOM node and subsequently interpreted as HTML through innerHTML usage patterns, creating an avenue for malicious actors to inject and execute arbitrary JavaScript code within the context of legitimate user sessions.
The technical flaw stems from the application's failure to properly sanitize or escape content before rendering it as HTML within the tooltip interface. When users interact with chess-related elements that trigger tooltip displays, the system extracts text content from underlying DOM nodes and processes it through innerHTML operations without adequate security controls. This pattern creates a direct path for attackers to inject malicious payloads that can execute in the browser context of other users who encounter the affected tooltips. The vulnerability is particularly concerning because it leverages legitimate application functionality to deliver malicious code, making detection more challenging and exploitation more effective.
The operational impact of this vulnerability extends beyond simple code execution, potentially allowing attackers to hijack user sessions, steal sensitive information, manipulate chess game data, or redirect users to malicious websites. Given that Lichess serves millions of users who engage in competitive chess activities, the potential for widespread exploitation exists. Attackers could craft tooltips containing malicious JavaScript that executes when other users view chess positions or game statistics, creating a vector for session hijacking, data exfiltration, or even account takeovers. The vulnerability affects applications that utilize the Lila framework, meaning any software built on this foundation could be similarly compromised.
Mitigation strategies for CVE-2025-48051 should focus on implementing proper input sanitization and output encoding mechanisms within the powertip.ts component. The recommended approach involves replacing direct innerHTML usage with safer alternatives such as textContent assignments or proper HTML sanitization libraries that strip malicious content before rendering. Security practitioners should also implement content security policies to limit script execution within tooltip contexts and ensure that all user-provided content undergoes rigorous validation before being processed by DOM manipulation functions. Additionally, regular security audits of DOM node operations and HTML rendering patterns should be conducted to prevent similar vulnerabilities from emerging in other components of the application.
This vulnerability aligns with CWE-79 which describes Cross-Site Scripting (XSS) and corresponds to techniques found in the ATT&CK framework under T1566 for Phishing and T1059 for Command and Scripting Interpreter. The attack vector demonstrates how seemingly benign UI components can become exploitation points when proper security controls are absent, highlighting the importance of defense-in-depth strategies. The vulnerability also relates to the broader category of insecure data handling practices that commonly appear in web applications, emphasizing the critical need for developers to follow secure coding standards and conduct thorough security testing throughout the development lifecycle.