CVE-2026-117968 in Firefox
Summary
by MITRE • 10/27/2026
Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, and Firefox ESR 153.6.
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Analysis
by VulDB Data Team • 10/27/2026
The identified vulnerability represents a critical memory management error within the Document Object Model core and HTML components of Mozilla Firefox browsers. Specifically classified as an use-after-free condition, this flaw occurs when the browser's rendering engine attempts to access or manipulate DOM elements that have already been deallocated from system memory. In complex web pages involving dynamic content updates, script execution, or rapid structural changes, the internal pointers tracking these objects may become stale if not properly synchronized with the garbage collection process. This discrepancy allows a maliciously crafted webpage to trigger operations on freed memory addresses, leading to undefined behavior within the browser's runtime environment.
From a technical perspective, use-after-free vulnerabilities are particularly dangerous because they can be leveraged to achieve arbitrary code execution under certain conditions. When an attacker controls the data written into the reused memory location before it is reallocated for another purpose, they may overwrite critical function pointers or object vtables within the browser's process space. This mechanism effectively allows the injection of malicious instructions that execute with the privileges of the user running the browser. The vulnerability resides in a core component responsible for parsing and rendering HTML content, meaning that simply visiting a compromised website is sufficient to trigger the exploit without requiring additional user interaction beyond normal browsing activities.
The operational impact of this flaw extends beyond simple application crashes or denial of service scenarios. While memory corruption can certainly cause the browser tab or entire process to terminate unexpectedly, resulting in data loss for unsaved work, the primary concern remains security compromise. Successful exploitation could allow an attacker to install malware, steal sensitive credentials stored within the browser session, perform keylogging, or pivot into internal network resources if the user has access to such environments. Given that Firefox is widely used across enterprise and personal sectors, this vulnerability poses a significant risk to data integrity and confidentiality for millions of users globally.
To mitigate these risks, immediate action must be taken by all affected parties. Users running versions prior to Firefox 159 should upgrade immediately to the latest stable release where the patch has been applied. Organizations utilizing Extended Support Release channels must ensure their systems are updated to at least version 115.44 or 153.6, depending on their specific support lifecycle requirements. In addition to software updates, defense-in-depth strategies such as enabling site isolation features and restricting script execution in untrusted domains can reduce the attack surface. Security teams should also monitor for indicators of compromise related to memory corruption exploits and ensure that endpoint detection systems are configured to flag anomalous browser behavior indicative of exploitation attempts.
This vulnerability aligns with Common Weakness Enumeration identifier CWE-416, which defines use-after-free errors as a distinct category of software defects leading to security vulnerabilities. Furthermore, the potential for remote code execution through this flaw maps directly to MITRE ATT&CK technique T1203, specifically referencing exploitation for drive-by processes where malicious code is executed without direct user interaction beyond visiting a web page. Understanding these classifications helps in prioritizing remediation efforts and aligning internal security controls with established industry standards for vulnerability management and threat mitigation.