CVE-2026-16382 in Firefox
Summary
by MITRE • 07/21/2026
Mitigation bypass in the DOM: Service Workers component. This vulnerability was fixed in Firefox 153.
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Analysis
by VulDB Data Team • 07/21/2026
This vulnerability represents a significant security flaw within Firefox's implementation of service workers, which are background processes that enable web applications to function offline and handle network requests without direct user interaction. The issue stems from how Firefox handles the Document Object Model within service worker contexts, specifically allowing for potential bypass of existing security mitigations that should normally prevent unauthorized access to sensitive resources or execution of malicious code through these components. Service workers operate in a privileged environment where they can intercept and modify network traffic, manage caching strategies, and even control user interface elements, making them attractive targets for attackers seeking to escalate privileges or circumvent browser security controls.
The technical nature of this flaw involves the manipulation of DOM access controls within service worker contexts, potentially allowing malicious code to bypass sandboxing mechanisms that should normally isolate these background processes from direct user interaction or sensitive data access. This represents a critical weakness in Firefox's security architecture as service workers are designed to operate with elevated privileges while maintaining strict isolation from the main document context. The vulnerability essentially allows for unauthorized access patterns that should be restricted by default, enabling attackers to potentially manipulate DOM elements or execute code that would normally be blocked by security policies. This bypass affects the fundamental integrity of Firefox's security model, particularly around how it manages trust boundaries between different execution contexts within the browser.
The operational impact of this vulnerability extends beyond simple privilege escalation as it undermines the core security assumptions underlying service worker implementations across modern web browsers. Attackers could potentially leverage this flaw to execute malicious code in contexts where such access should be restricted, leading to data exfiltration, cross-site scripting attacks, or even complete system compromise if combined with other vulnerabilities. The implications are particularly severe given that service workers are increasingly used for advanced web applications including progressive web apps, offline functionality, and complex network request handling. This vulnerability affects the browser's ability to maintain proper isolation between different security domains, potentially allowing attackers to access resources they should not be able to reach through normal user interaction or legitimate application behavior.
Security mitigations for this issue primarily involve updating to Firefox version 153 or later, which contains the necessary patches to address the DOM access control bypass in service worker components. Organizations should also implement comprehensive monitoring of service worker usage patterns and ensure that web applications properly validate all interactions with background processes. The fix addresses specific CWE categories related to improper access control and security bypass mechanisms, aligning with mitigations recommended under the ATT&CK framework for browser exploitation techniques. System administrators should review existing service worker implementations to identify potential attack vectors and ensure proper sandboxing practices are maintained. The vulnerability highlights the importance of continuous security assessment of browser components and the need for robust security controls even in seemingly isolated execution contexts where modern web applications expect elevated privileges for legitimate functionality.