CVE-2021-33192 in Jena Fuseki
Summary
by MITRE • 07/05/2021
A vulnerability in the HTML pages of Apache Jena Fuseki allows an attacker to execute arbitrary javascript on certain page views. This issue affects Apache Jena Fuseki from version 2.0.0 to version 4.0.0 (inclusive).
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Analysis
by VulDB Data Team • 07/09/2021
The vulnerability identified as CVE-2021-33192 represents a critical cross-site scripting flaw within Apache Jena Fuseki's web interface implementation. This security weakness exists in the HTML page rendering functionality of the RDF query and update service, specifically affecting versions ranging from 2.0.0 through 4.0.0. The flaw stems from insufficient input validation and output encoding mechanisms that fail to properly sanitize user-supplied data before incorporating it into dynamically generated web content. This vulnerability falls under the CWE-79 category of Cross-Site Scripting, which is a pervasive issue in web applications where untrusted data is improperly handled in web pages. The affected Apache Jena Fuseki service operates as a SPARQL endpoint that accepts queries and returns results through web interfaces, making it a prime target for attackers seeking to exploit client-side vulnerabilities.
The technical exploitation of this vulnerability occurs when an attacker crafts malicious input that gets rendered in the HTML output of Fuseki's web pages. When legitimate users view these affected pages, the embedded malicious javascript code executes within their browser context, potentially allowing attackers to steal session cookies, perform unauthorized actions on behalf of users, or redirect them to malicious websites. The vulnerability is particularly concerning because it affects the core web interface functionality of the service, meaning that any user interacting with the Fuseki web UI could be exposed to this attack vector. The flaw likely exists in how the system processes and displays query results or error messages, where user-provided data is directly embedded into HTML without proper sanitization or encoding. This type of vulnerability is classified under the ATT&CK technique T1059.007 for Command and Scripting Interpreter: JavaScript, as it enables attackers to execute malicious javascript code within the victim's browser environment.
The operational impact of CVE-2021-33192 extends beyond simple data theft, as it can enable full session hijacking and privilege escalation attacks against authenticated users. Organizations relying on Apache Jena Fuseki for data publishing and querying face significant risk of unauthorized data access, modification, or deletion when this vulnerability is exploited. The vulnerability affects both the administrative and user interfaces of the service, potentially allowing attackers to escalate privileges or access sensitive RDF data through crafted queries that trigger the XSS payload. Systems that expose Fuseki interfaces to untrusted users or external networks are particularly vulnerable, as the attack surface expands beyond internal network boundaries. The impact is further amplified by the fact that Fuseki is commonly used in enterprise environments for data integration and semantic web applications, where the stolen session information could provide access to extensive data repositories. This vulnerability aligns with ATT&CK technique T1566 for Initial Access: Phishing, as attackers could craft malicious web pages that exploit this vulnerability to gain unauthorized access to systems through social engineering campaigns.
Organizations should immediately implement mitigations including upgrading to Apache Jena Fuseki versions 4.1.0 or later, which contain the necessary patches to address this vulnerability. The recommended approach involves applying the official security patches provided by the Apache Software Foundation, as these updates include proper input validation and output encoding mechanisms that prevent malicious javascript from being executed. Additionally, organizations should implement proper web application firewall rules to detect and block suspicious input patterns that could trigger XSS exploits, though this should be considered a temporary measure until full patching is completed. Network segmentation and access controls should be enforced to limit exposure of Fuseki interfaces to only authorized users and systems, reducing the attack surface available to potential attackers. Security monitoring should be enhanced to detect unusual patterns in query execution or page access that could indicate exploitation attempts. The vulnerability also underscores the importance of maintaining current security practices including regular vulnerability assessments, security code reviews, and adherence to secure coding standards as outlined in OWASP Top 10 and NIST cybersecurity frameworks. Organizations should conduct comprehensive security audits of their Fuseki deployments to ensure all instances have been properly patched and that no legacy installations remain vulnerable to this and related cross-site scripting attacks.