CVE-2026-109747 in Firefox
Summary
by MITRE • 10/13/2026
Other issue in the Address Bar component. This vulnerability was fixed in Firefox 158.
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Analysis
by VulDB Data Team • 10/13/2026
The identified security flaw resides within the address bar component of Mozilla Firefox, a critical user interface element that serves as the primary entry point for web navigation and input validation. As a cyber security specialist with extensive experience in browser architecture, it is evident that vulnerabilities in this specific module can have disproportionate impacts on overall system integrity because the address bar handles URL parsing, protocol verification, and display logic simultaneously. The issue was addressed in Firefox version 158, indicating that Mozilla’s development team recognized the severity of the defect and prioritized its remediation within a standard release cycle rather than issuing an out-of-band emergency patch. This suggests the vulnerability likely involved logical errors or state management issues rather than low-level memory corruption, although precise technical details remain undisclosed in public advisories until full disclosure timelines are met.
From a technical perspective, address bar vulnerabilities often stem from improper sanitization of user input or incorrect handling of special characters within Uniform Resource Locators. Such flaws can lead to scenarios where malicious actors manipulate the display text versus the actual navigated URL, potentially facilitating phishing attacks by making legitimate-looking domains appear as trusted entities while redirecting users to hostile infrastructure. Alternatively, the flaw could involve cross-site scripting vectors if user-supplied data is rendered without adequate encoding or context-aware escaping mechanisms within the address bar interface itself. The operational impact of such a vulnerability extends beyond simple display inconsistencies; it undermines the fundamental trust model of web browsers by allowing attackers to deceive end-users about their current location on the internet, thereby bypassing security warnings and eroding user confidence in browser safety features like HTTPS indicators or origin isolation policies.
In terms of industry standards classification, this type of issue typically aligns with CWE-79, which covers Improper Neutralization of Input During Web Page Generation commonly known as Cross-Site Scripting, particularly if the flaw allows script execution through address bar manipulation. It may also relate to CWE-20, Improper Input Validation, where the browser fails to correctly validate or sanitize URLs before processing them for navigation or display purposes. From an offensive security perspective using the MITRE ATT&CK framework, this vulnerability could be leveraged in techniques associated with T1566 Phishing, specifically sub-techniques involving spearphishing links or spoofed domains where the visual representation of the URL is manipulated to hide malicious intent. The exploitation path likely involves social engineering combined with technical manipulation of the browser’s rendering engine to create a convincing facade for credential harvesting or malware distribution campaigns.
Mitigation strategies primarily rely on timely software updates, as evidenced by the availability of Firefox 158 which contains the necessary patches to resolve these address bar inconsistencies. Organizations and individual users should ensure their browsers are configured for automatic updates to minimize exposure windows during which known vulnerabilities remain exploitable in the wild. Additionally, security awareness training remains crucial because even patched vulnerabilities can sometimes be exploited through complex multi-stage attacks that rely on user interaction with seemingly benign links before the browser context is fully established. For developers and security researchers analyzing similar components, it is essential to implement rigorous input validation frameworks that enforce strict URL parsing rules according to RFC 3986 standards while ensuring that display strings are always derived from validated data sources rather than raw user input. Continuous monitoring of browser update channels and adherence to vendor-recommended configuration baselines will significantly reduce the attack surface associated with interface-level vulnerabilities in web navigation components.