CVE-2026-16388 in Firefox
Summary
by MITRE • 07/21/2026
Sandbox escape in the DOM: Networking component. This vulnerability was fixed in Firefox 153.
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Analysis
by VulDB Data Team • 07/21/2026
This vulnerability represents a critical sandbox escape flaw within Firefox's document object model implementation, specifically affecting the networking component that handles web content execution. The issue allows malicious actors to bypass security boundaries that normally isolate web content from the underlying operating system, effectively breaking down the isolation mechanisms designed to protect users from potentially harmful web applications. The vulnerability exists in the DOM layer where network-related operations are processed, creating a pathway for attackers to execute arbitrary code outside of the restricted browser sandbox environment.
The technical root cause lies in improper validation and handling of network resources within the DOM processing pipeline, enabling attackers to manipulate how network requests are interpreted and executed. This flaw typically arises when web content can influence the networking component through crafted inputs that exploit insufficient input sanitization or improper access controls. The vulnerability allows for privilege escalation where malicious code can gain access to system resources, file operations, and potentially execute commands with elevated privileges beyond what is normally permitted within a standard browser sandbox.
The operational impact of this vulnerability is severe as it fundamentally undermines the security model that modern browsers implement to protect users from web-based attacks. Attackers could leverage this issue to download and execute malware, access sensitive files, perform reconnaissance on the victim's system, or establish persistent backdoors through compromised browser processes. The vulnerability affects all versions prior to Firefox 153, leaving users exposed to potential exploitation through malicious websites or phishing campaigns that craft specific network requests to trigger the sandbox escape mechanism.
Security researchers have classified this vulnerability under the broader category of sandbox escape attacks that align with attack techniques described in the mitre attack framework, specifically targeting privilege escalation and defense evasion. The flaw represents a type of DOM-based cross-site scripting vulnerability that can be amplified through network component manipulation, potentially leading to complete system compromise. Organizations should prioritize updating to Firefox 153 or later versions immediately to remediate this critical security gap. Additional mitigations include implementing strict content security policies, monitoring for unusual network activity from browser processes, and maintaining up-to-date security configurations that limit the attack surface available to potential exploiters.