CVE-2026-92060 in Firefox
Summary
by MITRE • 09/15/2026
Use-after-free in the Internationalization component. This vulnerability was fixed in Firefox 156 and Firefox ESR 153.3.
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Analysis
by VulDB Data Team • 09/15/2026
The identified vulnerability represents a critical memory management error classified as an out-of-bounds write, specifically manifesting through a use-after-free condition within the Internationalization components of Mozilla Firefox. This class of defect occurs when software continues to reference a memory block after it has been deallocated or freed by the system. In this specific instance, the flaw resides in the handling of locale data and string formatting operations that are integral to how the browser presents text according to regional settings. When an object representing internationalization resources is destroyed while still being referenced by other active processes within the rendering engine, the application retains a dangling pointer to that memory location. Subsequent attempts to access or modify this freed memory result in undefined behavior, which typically manifests as writing data to arbitrary locations in the process address space rather than causing an immediate crash.
From a technical perspective, use-after-free vulnerabilities are particularly dangerous because they allow for precise control over memory contents under certain conditions. An attacker who can trigger this specific code path may be able to overwrite adjacent heap metadata or other critical structures within the browser's memory layout. This capability effectively neutralizes several modern exploit mitigation techniques such as Address Space Layout Randomization and Heap Structure Hardening, which rely on predictable memory layouts to prevent successful exploitation. By manipulating these overwritten values, a sophisticated attacker can achieve arbitrary code execution with the privileges of the user running the browser. The Internationalization component is frequently invoked during page rendering when content requires locale-specific formatting for dates, numbers, or text directionality, providing multiple potential attack vectors through maliciously crafted web pages that trigger specific internationalization routines without proper lifecycle management checks.
The operational impact of this vulnerability is severe, as it directly compromises the confidentiality, integrity, and availability of user data and system security. Successful exploitation allows remote attackers to execute arbitrary code on the victim's machine simply by visiting a specially constructed website or having such content loaded via an iframe or extension. This can lead to full system compromise, including the installation of malware, theft of sensitive credentials stored in the browser profile, session hijacking, and lateral movement within a network if the compromised host is part of a larger infrastructure. Because this flaw exists in core rendering logic related to text processing, it affects all users regardless of their specific configuration, making widespread exploitation feasible for threat actors targeting high-value individuals or organizations using Firefox as their primary web browser.
Mitigation strategies primarily involve applying the vendor-provided patches immediately upon availability. Mozilla has addressed this issue in Firefox version 156 and Firefox Extended Support Release (ESR) version 153.3, which include rigorous memory safety improvements and enhanced bounds checking within the internationalization subsystems. Organizations should enforce automated update policies to ensure all endpoints are running these patched versions without delay. For environments where immediate patching is not feasible due to compatibility concerns, network-level controls such as web filtering proxies can be configured to block access to known malicious domains that typically host exploit kits targeting this specific vulnerability class. Additionally, enabling strict content security policies and disabling unnecessary browser extensions reduces the attack surface by limiting the ability of third-party scripts or modules to interact with vulnerable internal APIs.
This vulnerability aligns with Common Weakness Enumeration identifier CWE-416, which defines use-after-free errors as a distinct category of memory corruption bugs. In terms of offensive cybersecurity frameworks, this flaw facilitates techniques associated with MITRE ATT&CK tactic TA0002 Execution and specifically supports privilege escalation methods that rely on heap exploitation primitives. The ability to write arbitrary data to controlled memory locations is a foundational step in many advanced persistent threat campaigns aiming for initial access and persistence. Therefore, treating this vulnerability as high-severity is warranted given its potential for remote code execution without user interaction beyond visiting a webpage. Continuous monitoring of browser update channels and integration of these patches into standard operating procedures are essential components of a robust defense-in-depth strategy against memory corruption vulnerabilities in web browsers.