CVE-2016-2803 in Bugzilla
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in the dependency graphs in Bugzilla 2.16rc1 through 4.4.11, and 4.5.1 through 5.0.2 allows remote attackers to inject arbitrary web script or HTML.
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Analysis
by VulDB Data Team • 11/29/2022
The vulnerability identified as CVE-2016-2803 represents a critical cross-site scripting flaw within Bugzilla's dependency graph functionality, affecting versions ranging from 2.16rc1 through 4.4.11 and 4.5.1 through 5.0.2. This issue resides in the web application's handling of user-supplied input within dependency visualization components, creating a persistent security weakness that enables malicious actors to execute arbitrary web scripts or HTML code within the context of affected users' browsers. The flaw specifically impacts the dependency graph feature which displays relationships between bugs and their interdependencies, making it a prime target for exploitation due to its interactive nature and widespread usage within the bug tracking system.
The technical implementation of this vulnerability stems from insufficient input validation and output encoding within the dependency graph rendering logic. When users create or modify bug dependencies, the system fails to properly sanitize user-provided data before incorporating it into dynamically generated HTML content. This inadequate sanitization allows attackers to inject malicious scripts that execute in the context of other users' sessions, particularly when they view the dependency graphs. The vulnerability manifests as a classic reflected XSS attack vector where attacker-controlled input flows through the application's processing pipeline and back into the user interface without proper contextual output encoding. This weakness aligns with CWE-79, which specifically addresses Cross-site Scripting vulnerabilities in web applications, and demonstrates the fundamental principle that all user-supplied data must be treated as untrusted and properly escaped for the target context.
The operational impact of CVE-2016-2803 extends beyond simple script execution, as it provides attackers with the capability to hijack user sessions, steal sensitive information, modify bug reports, and potentially escalate privileges within the Bugzilla environment. Attackers can craft malicious dependency relationships that, when viewed by other users, trigger script execution and enable various malicious activities including credential theft through session hijacking, data exfiltration, or even privilege escalation if users have administrative capabilities. The persistent nature of dependency graphs makes this vulnerability particularly dangerous as it can remain active for extended periods, continuously serving as an attack vector. This vulnerability also aligns with several ATT&CK tactics including initial access through malicious web content, privilege escalation via session hijacking, and credential access through session theft, making it a comprehensive threat to Bugzilla deployments.
Organizations utilizing affected Bugzilla versions should implement immediate mitigations including upgrading to patched versions where available, implementing strict input validation for all dependency-related fields, and applying output encoding to all dynamic content generated by the dependency graph feature. The recommended approach involves deploying proper HTML escaping mechanisms for all user-supplied content within the dependency visualization components, ensuring that special characters are properly encoded before insertion into HTML contexts. Additionally, implementing content security policies can provide an additional layer of protection against script execution, while regular security audits should verify that all user inputs are properly validated and sanitized before processing. The vulnerability serves as a reminder of the critical importance of input validation and output encoding in web applications, particularly in features that handle user-generated content and dynamic data visualization components.