CVE-2012-6708 identifies a cross-site scripting vulnerability in jQuery library versions before 1.9.0 that enables XSS attacks through improper differentiation between HTML content and CSS selectors in the main jQuery() function. This vulnerability achieves a CVSS score of 6.1 (Medium severity) with an EPSS score of 79.2 percentile and 1.4% exploitation probability, indicating significant attack potential for web applications using vulnerable jQuery versions with user-controlled input processing. The vulnerability details reveal that jQuery's main constructor function uses a flawed regular expression (rquickExpr) that looks for the '<' character anywhere in the input string to determine if content should be treated as HTML, allowing attackers to craft malicious selector strings containing HTML-like attributes that bypass normal parsing boundaries and execute JavaScript code. This creates substantial exploit risk for web applications that process user input through jQuery selectors, particularly affecting applications that dynamically construct jQuery selectors from user data, content management systems that allow custom selector queries, and JavaScript frameworks that utilize jQuery for DOM manipulation without proper input sanitization. The technical root cause lies in jQuery's src/core.js implementation where the rquickExpr regular expression incorrectly matches HTML patterns anywhere within input strings rather than anchoring the match to the beginning, classified as CWE-64 (Windows Shortcut Following), creating a vector for known exploited vulnerabilities targeting frontend JavaScript libraries. The vulnerability specifically exploits the confusion between CSS attribute selectors and HTML content, where malicious payloads like element[attribute='<img src="x" onerror="alert(1)" />'] can be interpreted as HTML due to the flawed regex matching, enabling script execution through attribute-based XSS vectors. With public exploits available and affecting JavaScript, Java, and over 11 other technologies including 50+ packages across multiple ecosystems, this vulnerability demonstrates the critical importance of proper input validation in popular JavaScript libraries. Mitigation strategies require upgrading to jQuery version 1.9.0 or later, which implements proper regex anchoring that requires HTML strings to explicitly start with the '<' character, significantly limiting attack vectors to scenarios where attackers can control the beginning of input strings. Organizations should prioritize identifying all web applications using vulnerable jQuery versions, audit JavaScript code for dynamic selector construction from user input, implement strict input validation and sanitization for all jQuery operations, and maintain updated CVE database records to track similar parsing vulnerabilities that could compromise web application security through client-side code execution and DOM manipulation attacks in frontend JavaScript frameworks.