CVE-2015-2711 in Firefox
Summary
by MITRE
Mozilla Firefox before 38.0 does not recognize a referrer policy delivered by a referrer META element in cases of context-menu navigation and middle-click navigation, which allows remote attackers to obtain sensitive information by reading web-server Referer logs that contain private data in a URL, as demonstrated by a private path component.
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Analysis
by VulDB Data Team • 05/17/2022
The vulnerability described in CVE-2015-2711 represents a critical flaw in Mozilla Firefox's implementation of referrer policy handling, specifically affecting versions prior to 38.0. This issue stems from the browser's failure to properly respect referrer policies that are communicated through HTML meta tags when users engage in context-menu navigation or middle-click navigation patterns. The fundamental problem lies in how Firefox processes these specific navigation methods, creating a discrepancy between the intended security controls and the actual behavior of the browser.
The technical flaw manifests when web pages include referrer policy directives within meta elements, which should instruct the browser on how to handle referrer information during navigation. However, Firefox versions before 38.0 ignored these policy directives during context-menu initiated navigation and middle-click operations, effectively bypassing the intended privacy controls. This behavior creates a significant information disclosure risk because sensitive data contained within URL paths can be inadvertently exposed to web servers through Referer headers that are logged by the server. The vulnerability is particularly concerning as it demonstrates a failure in the browser's security model to consistently enforce referrer policies across all navigation mechanisms.
The operational impact of this vulnerability extends beyond simple information disclosure to potentially compromise user privacy and security. Attackers can exploit this weakness by crafting web pages that include sensitive information in URL paths and then using context-menu or middle-click navigation to trigger the bypass. When users navigate through these specific methods, the server logs will contain full URLs including private path components, which can reveal personal information, session identifiers, or other sensitive data that should have been protected by the referrer policy. This vulnerability aligns with CWE-200, which addresses improper exposure of sensitive information, and represents a failure in the browser's implementation of the HTTP Referer header handling mechanism.
The security implications of CVE-2015-2711 are particularly significant when considering the ATT&CK framework's approach to information gathering techniques. This vulnerability enables adversaries to perform passive reconnaissance by analyzing web server logs to extract sensitive information that would normally be protected by referrer policy controls. The attack surface is widened because users can unknowingly expose private data through common navigation patterns that are typically considered safe. Organizations implementing web applications must consider this vulnerability when assessing their security posture, as it demonstrates how browser implementation flaws can undermine application-level security controls and create unexpected data leakage channels.
Mitigation strategies for this vulnerability require immediate browser updates to version 38.0 or later, where the referrer policy handling has been corrected to properly respect meta-element directives across all navigation methods. System administrators should also implement additional monitoring of web server logs to detect potential exposure of sensitive data through referrer headers, while developers should ensure their applications do not rely on browser behavior that might be inconsistent across different versions. The vulnerability highlights the importance of comprehensive testing of security controls across all user interaction patterns and demonstrates how seemingly minor implementation details can have significant security implications. Organizations should also consider implementing additional security measures such as Content Security Policy headers and server-side logging controls to provide defense-in-depth against similar information disclosure vulnerabilities.