CVE-2026-100760 in Firefox
Summary
by MITRE • 09/29/2026
Sandbox escape in the Security: Process Sandboxing component. This vulnerability was fixed in Firefox ESR 153.4 and Firefox 157.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 09/29/2026
The identified security flaw resides within the process sandboxing mechanisms of Mozilla Firefox, specifically affecting both the Extended Support Release version 153.4 and the standard release version 157. Process sandboxing is a critical defense-in-depth strategy employed by modern web browsers to isolate untrusted content from sensitive system resources. By restricting the permissions granted to individual browser processes, such as those handling webpage rendering or plugin execution, the browser ensures that even if an attacker successfully exploits a vulnerability within a rendered page, they are confined to a limited environment with minimal privileges. This isolation prevents malicious scripts from directly accessing the user's file system, network stack, or other critical operating system components without first escalating their privileges through additional exploitation steps.
The specific nature of this sandbox escape indicates that an attacker could bypass these restrictive boundaries under certain conditions. Typically, such vulnerabilities arise from errors in how the browser communicates with lower-level operating system APIs or manages inter-process communication channels. If a flaw exists in the logic governing permission checks or resource allocation within the sandboxed environment, it may allow code executed by a malicious website to break out of its designated container and execute commands with higher privileges than intended. This could potentially lead to arbitrary code execution on the victim's machine, allowing full control over the affected system depending on the user rights under which the browser is running.
From an operational perspective, successful exploitation of this vulnerability poses severe risks including data theft, installation of persistent malware, and use of the compromised device as part of a botnet. Attackers often leverage such flaws in conjunction with other vulnerabilities to create multi-stage attack chains that are difficult for endpoint detection systems to identify immediately. The impact extends beyond individual users to organizations deploying Firefox across their infrastructure, particularly if automatic updates are not strictly enforced or if legacy versions remain in use due to compatibility concerns.
To mitigate this risk, it is imperative that all instances of Mozilla Firefox and Firefox ESR be updated to the patched versions mentioned, specifically version 153.4 for Extended Support Release users and version 157 for general users. Organizations should ensure their patch management policies prioritize browser updates due to the high prevalence of web-based attacks targeting these components. Additionally, enabling automatic update checks can help maintain a consistent security posture by ensuring that critical fixes are applied promptly without requiring manual intervention from end-users or IT administrators.
This vulnerability aligns with common attack patterns documented in industry standards such as CWE-250, which refers to execution with unnecessary privileges, and CWE-787, involving out-of-bounds writes that can lead to memory corruption and subsequent privilege escalation. In the context of the MITRE ATT&CK framework, this type of flaw facilitates techniques related to Defense Evasion by allowing attackers to bypass sandboxing controls designed to contain malicious activity within a restricted environment. It also supports Initial Access vectors where web-based exploits are used as the entry point into an otherwise secure network perimeter. Continuous monitoring for anomalous process behavior and maintaining strict application control policies can further reduce the likelihood of successful exploitation even if similar vulnerabilities emerge in future releases.