CVE-2026-16383 in Firefox
Summary
by MITRE • 07/21/2026
Mitigation bypass in the DOM: Networking component. This vulnerability was fixed in Firefox 153 and Firefox ESR 140.13.
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Analysis
by VulDB Data Team • 07/21/2026
This vulnerability represents a sophisticated mitigation bypass within the Document Object Model implementation of the networking component in Mozilla Firefox browsers. The flaw specifically targets the DOM handling mechanisms that process network-related operations, allowing attackers to circumvent existing security controls designed to prevent unauthorized access or manipulation of web content. Such bypasses are particularly dangerous as they can undermine fundamental browser security models that rely on proper isolation between different execution contexts and network resources.
The technical implementation of this vulnerability stems from insufficient validation or improper handling of network-related data within the DOM parser or processing engine. When Firefox processes network requests or responses through its DOM interface, certain input validation checks may be bypassed or incorrectly evaluated, potentially allowing malicious actors to inject or manipulate network data in ways that should have been prevented by security policies. This type of vulnerability typically involves complex interactions between the browser's networking stack and its DOM manipulation capabilities, creating opportunities for privilege escalation or data exfiltration attacks.
The operational impact of this mitigation bypass extends beyond simple denial of service scenarios to potentially enable more severe security compromises including cross-site scripting attacks, man-in-the-middle interference, or unauthorized access to network resources. Attackers could exploit this vulnerability to manipulate how network requests are processed within the browser environment, potentially gaining access to sensitive information or redirecting traffic through malicious intermediaries. The vulnerability affects both regular Firefox releases and the extended support release version, indicating it represents a significant security concern that required immediate attention across multiple browser deployment scenarios.
Security mitigations for this vulnerability typically involve implementing stricter input validation procedures within the DOM networking component, ensuring proper sandboxing of network operations, and enhancing the isolation mechanisms between different browser contexts. Organizations should prioritize updating to Firefox version 153 or Firefox ESR 140.13 as these releases contain the necessary patches to address the underlying validation flaws. The vulnerability aligns with common weakness enumerations such as cwe-284 for improper access control and may relate to attack patterns involving privilege escalation through application-level weaknesses in web browser security models. Network administrators should monitor for potential exploitation attempts and implement additional defensive measures including web application firewalls and network traffic inspection tools to detect anomalous behavior that might indicate attempted exploitation of this class of vulnerability.