CVE-2018-6561 in Dojo Toolkit
Summary
by MITRE
dijit.Editor in Dojo Toolkit 1.13 allows XSS via the onload attribute of an SVG element.
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Analysis
by VulDB Data Team • 01/01/2020
The vulnerability CVE-2018-6561 affects the dijit.Editor component within the Dojo Toolkit version 1.13, presenting a cross-site scripting threat that exploits the improper handling of SVG elements. This issue arises when the editor processes content containing SVG markup with onload attributes, creating a pathway for malicious script execution in the context of the victim's browser session. The vulnerability demonstrates a classic input validation and output encoding failure that enables attackers to inject malicious JavaScript code through seemingly benign SVG elements.
The technical flaw stems from the editor's insufficient sanitization of SVG attributes, particularly the onload attribute which is commonly used in SVG graphics to execute scripts when the element is loaded. When a user loads content containing an SVG element with an onload handler, the Dojo Toolkit fails to properly escape or remove these dangerous attributes before rendering the content. This oversight creates an environment where attacker-controlled SVG markup can execute arbitrary JavaScript code in the victim's browser, bypassing normal security mechanisms that protect against cross-site scripting attacks. The vulnerability is classified as a CWE-79: Improper Neutralization of Input During Web Page Generation, which specifically addresses the failure to properly escape or filter user-supplied input that gets rendered as web content.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform a range of malicious activities including session hijacking, data exfiltration, and redirection to malicious sites. An attacker could craft SVG content containing malicious onload handlers that steal cookies, redirect users to phishing sites, or even deliver additional malware payloads. The attack vector is particularly concerning because SVG elements are commonly used in web applications for graphics and diagrams, making this vulnerability potentially widespread across applications that utilize the Dojo Toolkit for rich text editing. This vulnerability aligns with ATT&CK technique T1203: Exploitation for Client Execution, where adversaries leverage application vulnerabilities to execute malicious code in the context of the victim's browser.
Mitigation strategies for CVE-2018-6561 should focus on immediate patching of the Dojo Toolkit to version 1.13.1 or later, which includes proper sanitization of SVG attributes. Organizations should implement comprehensive input validation and output encoding mechanisms that specifically target SVG content, ensuring that onload and other potentially dangerous attributes are stripped or properly escaped before rendering. Additionally, security teams should consider implementing content security policies that restrict script execution from inline handlers and limit the use of potentially dangerous SVG attributes. The vulnerability highlights the importance of maintaining up-to-date libraries and frameworks, as well as implementing robust security testing procedures that include assessment of rich text editors and content rendering components to prevent similar issues from occurring in other parts of the application stack.