Executive Summary

CVE-2025-15056 is a Cross-Site Scripting (XSS) vulnerability in Quill version 2.0.3 caused by a lack of data validation in the HTML export feature, specifically in formula and video embeds. The vulnerability occurs because user-controlled input is directly embedded into HTML strings without escaping or sanitization, allowing attackers to inject malicious HTML or JavaScript. This can lead to arbitrary script execution in the victim's browser when the exported HTML is rendered. [2]

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Impact Analysis

This vulnerability can allow an attacker to execute arbitrary JavaScript in the context of a victim's browser by injecting malicious code into formula or video embeds in Quill's HTML export. This can lead to theft of sensitive information, session hijacking, or other malicious actions when the exported HTML is rendered without proper sanitization. The flaw is remotely exploitable without authentication but requires user interaction. [2]

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Detection Guidance

This vulnerability can be detected by inspecting HTML exports from Quill version 2.0.3 for unescaped user input in formula and video embeds. Specifically, look for HTML output containing suspicious or malicious payloads such as injected tags or event handlers (e.g., </span><img src=x onerror=alert(1)> or URLs with embedded JavaScript). Detection can involve searching exported HTML files or logs for these patterns. Commands such as grep or similar text search tools can be used, for example: grep -rE '</span><img|onerror=|onmouseover=' /path/to/exported/html. Additionally, monitoring web application inputs and outputs for unescaped HTML in formula or video embeds can help identify exploitation attempts. [2]

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Mitigation Strategies

Immediate mitigation steps include sanitizing or escaping all user-controlled input in formula and video embeds before exporting or rendering HTML. Since no patch is currently available, developers should implement input validation and output encoding to prevent injection of malicious HTML or JavaScript. Avoid rendering raw HTML from Quill's export functions without proper sanitization. Additionally, consider restricting or disabling the HTML export feature temporarily if feasible, and educate users about the risk of interacting with untrusted content. Monitoring for suspicious activity and applying web application firewall (WAF) rules to block typical XSS payloads can also help reduce risk. [2]

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