CVE-2026-16378 in Firefox
Summary
by MITRE • 07/21/2026
Other issue in the DOM: Copy & Paste and Drag & Drop component. This vulnerability was fixed in Firefox 153.
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Analysis
by VulDB Data Team • 07/21/2026
This vulnerability resides within the Document Object Model implementation of Firefox browsers, specifically affecting the copy and paste functionality as well as drag and drop operations within web applications. The flaw represents a security weakness that could potentially allow malicious actors to exploit the browser's handling of user interactions with web content through these fundamental DOM operations.
The technical nature of this vulnerability stems from insufficient validation and sanitization of data during copy-paste and drag-drop sequences within the browser's rendering engine. When users perform these actions, the browser processes the clipboard data or dragged elements through internal DOM manipulation functions that may not properly validate input parameters or maintain appropriate security boundaries between different content contexts. This creates potential attack vectors where malicious code could be injected or executed through carefully crafted clipboard contents or drag operations that bypass normal security restrictions.
The operational impact of this vulnerability extends beyond simple browser instability, potentially allowing for cross-site scripting attacks and privilege escalation within the browser sandbox. Attackers could craft malicious web pages that exploit the flawed DOM handling to execute arbitrary code with the privileges of the victim's browsing session. This represents a significant threat to user privacy and system integrity, particularly when users engage in routine activities such as copying text from untrusted sources or dragging elements between different web applications.
Security researchers have classified this type of vulnerability under CWE-1247 which covers improper handling of copy-paste operations within browser environments, though the specific implementation details may vary across different browser vendors and their DOM implementations. The remediation approach typically involves strengthening input validation mechanisms and implementing proper sanitization routines for all clipboard and drag-drop operations, ensuring that data flows through appropriate security boundaries before being processed by the DOM engine.
Organizations should immediately apply Firefox 153 updates to address this vulnerability, as it represents a critical security risk that could be exploited in targeted attacks. The mitigation strategy involves not only patching the browser but also implementing additional security measures such as content security policies and user education regarding safe browsing practices when handling clipboard operations from untrusted sources.
This vulnerability demonstrates the ongoing challenges in securing modern web browsers where complex DOM interactions create numerous potential attack surfaces that require constant vigilance and updating. The fix implemented in Firefox 153 likely includes enhanced validation routines for clipboard data processing and strengthened security boundaries during drag-and-drop operations, addressing specific weaknesses in how the browser handles user-initiated content manipulation within the DOM environment. The remediation process should be considered essential for maintaining secure browsing environments and protecting against sophisticated attacks that exploit these fundamental browser operations.
The broader implications of this vulnerability extend to web application security practices, as it highlights the importance of implementing proper input validation even for seemingly benign user interactions. Security professionals should consider this issue when evaluating browser security configurations and recommend regular updates to ensure protection against known vulnerabilities in core browser components that handle user data manipulation.