CVE-2018-11093 in CKeditor
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in the Link package for CKEditor 5 before 10.0.1 allows remote attackers to inject arbitrary web script through a crafted href attribute of a link (A) element.
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Analysis
by VulDB Data Team • 02/07/2020
The CVE-2018-11093 vulnerability represents a critical cross-site scripting flaw within the Link package of CKEditor 5 versions prior to 10.0.1. This vulnerability resides in the HTML sanitization and rendering mechanisms of the rich text editor, specifically when processing anchor elements with href attributes. The flaw enables remote attackers to execute malicious scripts in the context of the victim's browser session, potentially leading to unauthorized actions and data theft. The vulnerability is classified under CWE-79 as a failure to sanitize user input before rendering it in a web page, making it a classic XSS vector that exploits the trust relationship between the web application and the end user.
The technical exploitation of this vulnerability occurs when a malicious actor crafts a specially formatted href attribute containing script code that gets executed when the link is rendered in a browser. The CKEditor 5 Link package fails to properly validate or escape the href attribute values, allowing attackers to inject JavaScript code that executes in the context of the victim's browser. This occurs because the editor does not adequately filter or encode user-provided content before storing or rendering it, creating an environment where attacker-controlled scripts can be executed. The vulnerability is particularly dangerous because CKEditor is widely used in content management systems, web applications, and enterprise platforms where users can input rich text content.
The operational impact of CVE-2018-11093 extends beyond simple script execution to potentially compromise entire user sessions and applications. Attackers could leverage this vulnerability to steal session cookies, redirect users to malicious sites, deface web pages, or perform actions on behalf of authenticated users. The vulnerability affects any web application that utilizes CKEditor 5 with the Link package and does not properly validate user input, creating a significant risk for organizations that rely on rich text editing capabilities. The attack vector is particularly insidious because it can be delivered through seemingly benign content creation activities, making it difficult to detect and prevent through traditional security measures.
Organizations should prioritize immediate patching of affected CKEditor 5 installations to version 10.0.1 or later, which includes proper input sanitization and validation mechanisms. Additional mitigations include implementing strict content security policies, employing web application firewalls, and conducting thorough input validation at multiple layers of the application stack. The vulnerability demonstrates the importance of proper HTML sanitization and input validation practices, aligning with ATT&CK technique T1059.001 for command and scripting interpreter execution. Security teams should also consider implementing automated testing for XSS vulnerabilities in their development pipelines and conducting regular security assessments of rich text editing components within their applications.