CVE-2021-25967 in CKAN
Summary
by MITRE • 12/01/2021
In CKAN, versions 2.9.0 to 2.9.3 are affected by a stored XSS vulnerability via SVG file upload of users’ profile picture. This allows low privileged application users to store malicious scripts in their profile picture. These scripts are executed in a victim’s browser when they open the malicious profile picture
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Analysis
by VulDB Data Team • 12/08/2021
The vulnerability CVE-2021-25967 represents a critical stored cross-site scripting flaw in CKAN versions 2.9.0 through 2.9.3 that specifically targets the user profile picture upload functionality. This issue falls under the CWE-79 category of Cross-Site Scripting, where malicious code can be persistently stored and executed within the application's environment. The vulnerability exploits the lack of proper input validation and sanitization when processing SVG file uploads, which are commonly used for profile images due to their scalability and vector nature. Attackers can leverage this weakness by uploading specially crafted SVG files containing malicious JavaScript code that gets stored on the server and subsequently executed whenever other users view the compromised profile picture.
The technical implementation of this vulnerability stems from CKAN's insufficient validation of SVG file content during the upload process. SVG files are inherently powerful because they support embedded JavaScript through the <script> tag and can execute code when rendered in web browsers. When users upload profile pictures, the system should validate and sanitize all uploaded files to prevent execution of malicious code. However, in affected versions, the application fails to properly sanitize SVG content, allowing attackers to embed malicious payloads within the image file itself. This creates a persistent threat where the malicious code remains stored on the server and executes in victims' browsers without requiring additional interaction from the user.
The operational impact of this vulnerability extends beyond simple data theft or defacement, as it enables attackers to perform sophisticated attacks through the compromised user accounts. When a victim views a profile picture containing malicious SVG code, their browser executes the embedded JavaScript, potentially allowing attackers to steal session cookies, redirect users to malicious sites, or perform actions on behalf of the victim. This creates a vector for privilege escalation attacks where low-privileged users can leverage this vulnerability to compromise other users within the same CKAN instance. The stored nature of the XSS means that even if the original attacker leaves the system, the malicious code continues to execute against unsuspecting users who view the compromised profile picture, making this a particularly dangerous threat vector.
Security mitigations for this vulnerability should focus on implementing comprehensive input validation and sanitization of all uploaded SVG files. Organizations should deploy strict content validation that strips or encodes all potentially dangerous elements from SVG files, including script tags, event handlers, and external references. The recommended approach involves using dedicated SVG sanitization libraries that can properly parse and clean SVG content while preserving legitimate image functionality. Additionally, implementing Content Security Policy headers can provide an additional layer of protection by restricting script execution within the application context. Organizations should also consider implementing proper access controls and monitoring for suspicious upload activities, as outlined in the ATT&CK framework's technique T1566 for credential access through social engineering. Regular security updates and patch management are essential to ensure that all instances of CKAN remain protected against this and similar vulnerabilities.