CVE-2019-10062 in Aurelia
Summary
by MITRE • 05/14/2021
The HTMLSanitizer class in html-sanitizer.ts in all released versions of the Aurelia framework 1.x repository is vulnerable to XSS. The sanitizer only attempts to filter SCRIPT elements, which makes it feasible for remote attackers to conduct XSS attacks via (for example) JavaScript code in an attribute of various other elements. An attacker might also exploit a bug in how the SCRIPT string is processed by splitting and nesting them for example.
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Analysis
by VulDB Data Team • 05/16/2021
The vulnerability identified as CVE-2019-10062 affects the Aurelia framework 1.x repository and represents a critical cross-site scripting weakness in the HTMLSanitizer class implementation. This security flaw exists within the html-sanitizer.ts file and impacts all released versions of the framework, creating a persistent threat vector that has remained unaddressed across the entire 1.x release line. The vulnerability stems from an incomplete sanitization approach that fails to adequately protect against malicious content injection attempts, particularly when attackers leverage alternative HTML element attributes to bypass the limited filtering mechanism.
The technical implementation of this vulnerability demonstrates a fundamental flaw in the sanitization logic where the HTMLSanitizer class focuses exclusively on filtering SCRIPT elements while neglecting other potential attack vectors. This narrow approach creates a false sense of security as attackers can successfully inject malicious JavaScript code through various HTML attributes of different elements, including but not limited to onclick, onmouseover, or other event handlers. The sanitizer's processing of SCRIPT strings becomes particularly problematic when attackers employ sophisticated techniques such as splitting and nesting script elements to circumvent the filtering mechanism, effectively rendering the security controls ineffective.
From an operational perspective, this vulnerability creates significant risk for applications utilizing the Aurelia framework, as remote attackers can exploit the weakness to execute arbitrary JavaScript code within the context of affected web applications. The impact extends beyond simple script execution to potentially enable full session hijacking, data theft, and privilege escalation attacks. The vulnerability's exploitation requires minimal technical sophistication, making it particularly dangerous as it can be leveraged by attackers with basic knowledge of web application security principles. Organizations relying on Aurelia framework 1.x applications face substantial risk of user data compromise and application integrity violations.
The vulnerability aligns with CWE-79, which describes cross-site scripting flaws, and demonstrates characteristics consistent with CWE-116, representing improper encoding or escaping of output. From an ATT&CK framework perspective, this vulnerability maps to T1203, which covers exploitation for privilege escalation through web application vulnerabilities, and T1059, representing execution through scripting. The security implications extend to T1566, covering credential access through malicious web content, and T1190, representing exploitation of vulnerabilities in web applications. Organizations should prioritize immediate mitigation through framework version upgrades or implementation of additional security controls to address this exposure.
Mitigation strategies should include immediate upgrade to supported versions of the Aurelia framework where the vulnerability has been resolved, implementation of additional input validation layers, and deployment of web application firewalls to detect and prevent exploitation attempts. Security teams should also implement comprehensive monitoring for suspicious script injection attempts and establish incident response procedures specifically addressing this vulnerability type. The remediation process must include thorough code reviews to identify other potential sanitization weaknesses and implementation of more robust HTML sanitization libraries that properly handle all potential attack vectors rather than relying on incomplete filtering approaches.