CVE-2012-6708 in jQuery
Summary
by MITRE
jQuery before 1.9.0 is vulnerable to Cross-site Scripting (XSS) attacks. The jQuery(strInput) function does not differentiate selectors from HTML in a reliable fashion. In vulnerable versions, jQuery determined whether the input was HTML by looking for the '<' character anywhere in the string, giving attackers more flexibility when attempting to construct a malicious payload. In fixed versions, jQuery only deems the input to be HTML if it explicitly starts with the '<' character, limiting exploitability only to attackers who can control the beginning of a string, which is far less common.
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Analysis
by VulDB Data Team • 07/10/2025
The vulnerability described in CVE-2012-6708 represents a critical cross-site scripting weakness in jQuery versions prior to 1.9.0, specifically affecting the jQuery(strInput) function's handling of input validation. This flaw stems from an insufficient implementation of HTML versus selector differentiation within the library's core functionality. The vulnerability operates under CWE-79 which classifies improper neutralization of input during web page generation, making it a direct descendant of the well-known XSS attack vector. The issue manifests when jQuery processes user-provided input through its selector engine, where the library's logic fails to properly distinguish between legitimate HTML content and malicious script payloads.
The technical root cause lies in jQuery's flawed string analysis mechanism that previously examined the entire input string for the presence of the '<' character to determine if the input should be treated as HTML. This simplistic approach created a significant security gap because attackers could craft malicious payloads by placing the '<' character at any position within their input, effectively bypassing the intended HTML detection mechanism. The vulnerability enables attackers to inject malicious scripts that execute in the context of the victim's browser when the vulnerable jQuery function processes the crafted input. This behavior aligns with ATT&CK technique T1566.001 which describes the exploitation of web applications through injection attacks, particularly focusing on cross-site scripting vulnerabilities.
The operational impact of this vulnerability extends far beyond simple script execution, as it allows attackers to perform session hijacking, deface web applications, steal sensitive user data, and potentially escalate privileges within the affected web environment. Any web application utilizing vulnerable jQuery versions and processing user input through the affected function becomes susceptible to these attacks. The exploitability is particularly concerning because it requires minimal input control from attackers, who can manipulate the input string to include the '<' character at any position to bypass the flawed validation. This weakness essentially provides attackers with multiple attack vectors since they don't need to control the exact beginning of the input string, only need to ensure the presence of the '<' character somewhere within their payload.
The remediation for this vulnerability required a fundamental change in jQuery's input validation logic, where the fixed versions implemented stricter criteria that only treat input as HTML when it explicitly begins with the '<' character. This change significantly reduces the attack surface by limiting the conditions under which malicious input can be interpreted as HTML content. Organizations affected by this vulnerability must upgrade to jQuery 1.9.0 or later versions, though this upgrade should be performed carefully to ensure compatibility with existing web applications. The fix represents a common security pattern where input validation is strengthened through more precise character position checking rather than broad pattern matching. Security teams should also implement additional layers of protection such as content security policies, input sanitization at multiple layers, and regular security assessments to prevent similar vulnerabilities from emerging in other components of their web applications.