CVE-2026-109740
Description
A flaw was found in Firefox. Incorrect boundary condition handling in the Win32 widget component allows an attacker to escape the browser's restricted sandbox environment. An attacker who has compromised a sandboxed content process could exploit this vulnerability to achieve privilege escalation and execute arbitrary code on the underlying operating system.
Statement
This vulnerability is rated as Important severity because escaping the client sandbox allows an attacker who has compromised a content process to execute arbitrary code with the privileges of the host process. However, the vulnerable boundary condition resides exclusively within the Win32 widget subsystem developed for Microsoft Windows. Red Hat Enterprise Linux builds of Firefox and Thunderbird utilize the GTK windowing implementation and do not include the Windows-specific code, preventing exposure in Red Hat environments.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.1 | N/A | 9.6 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | Required | N/A | Required |
| Scope | Changed | N/A | Changed |
| Confidentiality | Low | N/A | High |
| Integrity Impact | Low | N/A | High |
| Availability Impact | None | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Understanding the Weakness (CWE)
Access Control
Technical Impact: Gain Privileges or Assume Identity; Bypass Protection Mechanism
The exploitation of a weakness in low-privileged areas of the software can be leveraged to reach higher-privileged areas without having to overcome any additional obstacles, extending the scope of the damage to higher-privileged users..
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