CVE-2026-118002 in Firefox
Summary
by MITRE • 10/27/2026
Information disclosure due to race condition in the Networking component. This vulnerability was fixed in Firefox 159 and Firefox ESR 153.6.
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Analysis
by VulDB Data Team • 10/27/2026
The identified security flaw resides within the networking subsystem of Mozilla Firefox, specifically manifesting as a race condition that leads to information disclosure. A race condition occurs when software behavior depends on the relative timing or interleaving of multiple threads or processes, often arising from improper synchronization mechanisms during concurrent operations. In this specific instance, the vulnerability allows an attacker who can trigger simultaneous network requests or manipulate the state of networking components to access sensitive data that should remain isolated or protected by security boundaries. The core technical flaw involves a window where shared resources are accessed without adequate locking or atomicity guarantees, enabling one execution path to read intermediate states or cached credentials before they have been properly sanitized or overwritten by subsequent operations.
This type of vulnerability is classified under CWE-362, which covers concurrent execution using shared resources with improper synchronization. The exploitation vector typically requires the attacker to craft a scenario where multiple asynchronous network events occur in close succession, potentially leveraging browser extensions, complex web applications, or specific API calls that interact heavily with the networking stack. By carefully timing these interactions, an adversary may be able to intercept sensitive information such as authentication tokens, session cookies, or private data associated with other tabs or contexts within the same browser instance. The impact is primarily confidentiality-related, as it compromises the integrity of user privacy and potentially exposes credentials that could lead to account takeover if combined with other attack vectors like cross-site scripting or phishing.
From a threat modeling perspective aligned with MITRE ATT&CK frameworks, this vulnerability falls under techniques associated with Collection via Browser Hijacking or Data from Information Repositories, specifically where an attacker leverages local system access through the browser environment to exfiltrate data. The lack of strict isolation between concurrent network operations creates a side-channel effect that can be exploited for unauthorized data retrieval. This is particularly dangerous in enterprise environments or multi-user systems where session persistence and credential storage are critical components of daily workflow, as it undermines the trust model assumed by modern web browsers regarding sandboxing and origin separation.
The vulnerability has been addressed in Firefox version 159 and Firefox Extended Support Release (ESR) version 153.6 through rigorous code review and patch implementation that likely involved adding proper synchronization primitives such as mutexes or atomic operations to the networking component's critical sections. These fixes ensure that shared resources are accessed sequentially or with appropriate locks, eliminating the timing window that allowed for data leakage. Users operating older versions of Firefox remain at risk if they engage in activities involving complex network interactions or untrusted web content that can trigger these concurrent states.
To mitigate this vulnerability and similar race condition risks, organizations should prioritize immediate patching to ensure all client machines are running version 159 or later for standard releases, or 153.6 or later for ESR channels. Additionally, implementing strict Content Security Policies (CSP) can help limit the scope of scripts that interact with networking APIs, reducing the attack surface available to potential exploiters. Regular security audits focusing on concurrency issues in custom browser extensions or embedded web views are also recommended, as race conditions often stem from complex asynchronous code paths that are difficult to detect through static analysis alone. Continuous monitoring for anomalous network behavior and enforcing least-privilege principles for application permissions further hardens the environment against exploitation of such timing-based flaws.