CVE-2026-84117 in Firefox
Summary
by MITRE • 09/01/2026
Privilege escalation in Firefox for Android. This vulnerability was fixed in Firefox 155.
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Analysis
by VulDB Data Team • 09/01/2026
The discovery of a privilege escalation vulnerability within Mozilla Firefox for Android represents a significant security concern, as it allows an attacker to execute code with elevated privileges beyond those intended by the browser's sandboxing mechanisms. In mobile environments like Android, applications operate under strict permission models designed to isolate user data and system resources from potentially malicious actors. When this isolation is compromised through privilege escalation, the integrity of both the application environment and the underlying operating system can be severely undermined. This specific flaw was addressed in Firefox version 155, indicating that prior versions were susceptible to exploitation where a lower-privileged process could manipulate internal states or access restricted APIs to gain higher-level control.
The technical nature of such vulnerabilities often stems from improper checks on user input or insufficient validation when transitioning between different security contexts within the browser engine. In Firefox for Android, this might involve interactions with native components via JNI (Java Native Interface) or misconfigured permissions in the application manifest that allow unintended cross-process communication. An attacker could craft a malicious webpage or exploit a third-party add-on to trigger specific code paths that bypass these checks. By doing so, they can execute arbitrary commands on the device, access sensitive user data such as saved passwords and browsing history, or install additional malware without explicit user consent. The absence of robust boundary enforcement between the web content process and more privileged browser processes is a common root cause for this class of defects in complex software architectures like browsers.
The operational impact of successfully exploiting this vulnerability extends beyond simple data theft. It enables persistent access to the device, allowing attackers to monitor network traffic, intercept sensitive communications, or use the compromised device as part of a botnet. Furthermore, because Firefox is often used for banking and other financial transactions on mobile devices, such an escalation poses direct risks to user finances and personal identity security. The ability to escalate privileges effectively neutralizes many of the protective layers provided by Android's permission system, making detection difficult for standard antivirus solutions that rely on signature-based analysis rather than behavioral monitoring of privilege transitions.
Mitigation strategies primarily involve immediate software updates to ensure users are running Firefox version 155 or later, where these specific code paths have been hardened and validated. For organizations deploying Firefox across multiple devices, centralized management tools should be configured to enforce this minimum version requirement automatically. Additionally, developers must adhere to the principle of least privilege when designing browser components, ensuring that each process operates with only the permissions necessary for its function. Regular security audits focusing on inter-process communication boundaries and JNI bindings are essential to prevent similar issues in future releases. Users can further reduce risk by enabling automatic updates within their device settings and avoiding the installation of unverified add-ons or extensions from unofficial sources, which often serve as initial vectors for such exploits.
This incident aligns with common vulnerability classifications found in industry standards such as CWE-269 Improper Privilege Management and CWE-78 OS Command Injection if command execution is involved. From a threat intelligence perspective, the exploitation technique likely maps to MITRE ATT&CK techniques related to privilege escalation on mobile platforms, specifically those involving local exploits or abuse of system services. Understanding these mappings helps security teams prioritize patching efforts and configure detection rules in endpoint protection systems to identify anomalous behavior associated with such attacks. Continuous monitoring for unusual process creation events originating from browser processes can provide an additional layer of defense against zero-day variants that may not yet have a known fix available.