CVE-2016-5682 in Swagger-UI
Summary
by MITRE
Swagger-UI before 2.2.1 has XSS via the Default field in the Definitions section.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 08/28/2020
The vulnerability identified as CVE-2016-5682 affects Swagger-UI versions prior to 2.2.1 and represents a cross-site scripting vulnerability that emerges from improper input validation within the Definitions section of the API documentation interface. This flaw specifically targets the Default field parameter, which when manipulated by an attacker can execute malicious scripts in the context of a victim's browser session. The vulnerability exists because the Swagger-UI component fails to adequately sanitize user-provided input before rendering it within the web interface, creating an avenue for persistent XSS attacks that can compromise user sessions and potentially exfiltrate sensitive data.
The technical implementation of this vulnerability stems from the lack of proper input sanitization mechanisms within the Swagger-UI framework's handling of default values in API definitions. When API developers or consumers provide default values that contain malicious script payloads within the Definitions section, these inputs are directly embedded into the HTML output without appropriate encoding or validation. This allows an attacker to inject JavaScript code that executes in the browser context of any user viewing the affected API documentation page. The vulnerability is particularly concerning because API documentation interfaces are often accessible to multiple users within an organization, increasing the potential attack surface and impact.
From an operational perspective, this vulnerability can have significant consequences for organizations relying on Swagger-UI for API documentation and testing. An attacker who successfully exploits this vulnerability can execute arbitrary JavaScript code in the context of authenticated users, potentially leading to session hijacking, data exfiltration, or privilege escalation within the affected applications. The attack vector is relatively straightforward, requiring only that an attacker can influence the Default field values in API definitions, which may be possible in environments where API documentation is publicly accessible or where untrusted users can contribute to API specifications. This vulnerability aligns with CWE-79, which specifically addresses cross-site scripting flaws in web applications.
Organizations should prioritize immediate remediation by upgrading to Swagger-UI version 2.2.1 or later, which includes proper input sanitization and validation mechanisms. Additional mitigations include implementing content security policies that restrict script execution within the API documentation interface, regularly auditing API definition files for suspicious content, and restricting access to the documentation interface to authorized personnel only. The vulnerability demonstrates the importance of input validation in web applications and aligns with ATT&CK technique T1213, which covers data from information repositories, as the attack targets the documentation repository that contains sensitive API information. Security teams should also consider implementing web application firewalls to detect and block suspicious script payloads and establish monitoring procedures to identify potential exploitation attempts against API documentation interfaces.