CVE-2026-117950 in Firefox
Summary
by MITRE • 10/27/2026
Incorrect boundary conditions 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 security issue resides within the Document Object Model core and HTML components of Mozilla Firefox, specifically involving incorrect boundary conditions during memory management operations. This type of vulnerability typically arises when the browser engine fails to properly validate array indices or buffer lengths before performing read or write actions on allocated memory regions. In complex web rendering engines like Gecko, which powers Firefox, the DOM is a critical interface that allows scripts and internal processes to interact with page content. When boundary checks are insufficient or incorrectly implemented, an attacker can manipulate input data to cause out-of-bounds reads or writes. These errors do not necessarily lead to immediate crashes but create unstable memory states that can be exploited for more severe attacks. The vulnerability was addressed in Firefox version 159 as well as the extended support release versions 115.44 and 153.6, indicating a targeted patching strategy to ensure stability across both current development branches and long-term maintenance releases.
From a technical perspective, incorrect boundary conditions often map directly to CWE-125 Out-of-bounds Read or CWE-787 Out-of-bounds Write depending on the specific nature of the memory access violation. If the flaw allows reading beyond allocated buffers, it may lead to information disclosure where sensitive data from adjacent memory locations is exposed to malicious scripts running within a compromised webpage context. Conversely if the vulnerability permits writing outside buffer limits it can result in heap corruption which undermines the integrity of the browser's internal structures such as object headers or function pointers. This type of flaw is particularly dangerous because modern browsers employ various mitigation techniques like ASLR and DEP but these defenses are often bypassed through precise memory manipulation enabled by out-of-bounds access. The presence of this vulnerability suggests a gap in the input validation logic within the DOM parsing or rendering pipeline where edge cases involving malformed HTML or specific JavaScript interactions were not adequately handled.
The operational impact of such vulnerabilities is significant as they can be triggered remotely via malicious web pages without requiring user interaction beyond visiting the site if combined with other techniques like social engineering or drive-by download mechanisms. An attacker could potentially achieve arbitrary code execution by chaining this memory corruption flaw with a separate exploit technique to gain control over the browser process and subsequently the underlying operating system. This aligns with ATT&CK tactic T1203 Exploitation for Client Execution where adversaries leverage software vulnerabilities in client applications to establish initial access or escalate privileges within the user context. The risk is amplified by the widespread usage of Firefox across enterprise environments where browsers are often used as gateways to internal resources making any compromise potentially impactful on organizational security posture.
Mitigation strategies primarily involve ensuring that all affected systems are updated to include the patched versions mentioned above which correct the boundary validation logic within the DOM and HTML components. Administrators should enforce automatic update policies for Firefox installations across their networks to minimize exposure windows during which unpatched vulnerabilities remain active. Additionally implementing strict content security policies can help mitigate potential exploitation by restricting inline script execution and limiting access to external resources thereby reducing the attack surface available to malicious actors attempting to leverage this flaw. Regular vulnerability scanning and penetration testing focused on browser-based attacks should also be conducted to identify similar implementation errors in custom web applications or extensions that interact with DOM elements using unsafe patterns.