Privilege Escalation in Firefox by Mozilla

CVE-2026-4717

What is CVE-2026-4717?

CVE-2026-4717 is a privilege escalation vulnerability found in the Firefox web browser and its related application, Thunderbird. Specifically, this flaw resides in the Netmonitor component, which is an integral part of these software products, responsible for network monitoring functionalities. The vulnerability impacts versions of Firefox prior to 149, Firefox Extended Support Release (ESR) below 140.9, as well as earlier versions of Thunderbird that are below 149 and ESR below 140.9.

If exploited, this vulnerability could allow an attacker to escalate their privileges within the application, potentially granting them unauthorized access to sensitive information or system controls. Such access can be particularly damaging within organizational settings, where sensitive data and internal resources must be safeguarded against malicious activities. The technical details surrounding this vulnerability indicate that it could lead to unauthorized operations or the manipulation of the application’s functionality, thereby compromising the overall security of the environment.

Potential impact of CVE-2026-4717

1. Unauthorized Privilege Escalation: Attackers could exploit this vulnerability to gain higher-level access within the affected applications, enabling them to perform actions that should be restricted, potentially altering or accessing sensitive data.

2. Data Breaches: Once elevated privileges are obtained, attackers may access confidential information stored within Firefox and Thunderbird, leading to significant data breaches that could expose personal information, corporate secrets, or proprietary data.

3. System Compromise: By leveraging the vulnerability to execute malicious actions, an attacker can compromise the underlying system, which could facilitate the installation of malware or additional exploits, further jeopardizing the integrity and security of the organization’s IT infrastructure.

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