CVE-2026-100775 in Firefox
Summary
by MITRE • 09/29/2026
Sandbox escape in the Graphics component. This vulnerability was fixed in Firefox ESR 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 09/29/2026
The identified security issue represents a critical sandbox escape within the Graphics component of Mozilla Firefox browsers. This type of vulnerability allows malicious content executed within the browser's restricted environment to break out of its designated boundaries and interact with the underlying operating system or other processes outside the intended scope. The graphics subsystem is particularly sensitive because it handles rendering operations that often require elevated privileges or direct access to hardware resources, making a successful exploitation potentially catastrophic for user security. By escaping the sandbox, an attacker could execute arbitrary code on the victim's machine, leading to full system compromise rather than just browser-level isolation failure.
The technical flaw likely stems from improper validation of input data passed between different components of the graphics stack or insufficient checks when handling complex rendering commands. In many modern browsers, the renderer operates in a low-privilege sandboxed process while higher-level tasks occur in parent processes with more permissions. If an attacker can craft specific graphical payloads that trigger undefined behavior or memory corruption within this boundary layer, they may achieve arbitrary read/write primitives. These primitives are typically leveraged to bypass address space layout randomization and other mitigation techniques, ultimately allowing the execution of native code outside the sandbox environment. Such vulnerabilities often involve race conditions, integer overflows, or use-after-free errors in how graphics contexts manage memory allocations during rendering operations.
The operational impact of this vulnerability is severe due to its potential for remote code execution without user interaction if triggered via a malicious website. An attacker could host a specially crafted webpage containing exploit code that targets the graphics engine's processing logic. When a victim visits this page, the browser attempts to render the content, inadvertently triggering the flaw and allowing the sandbox escape. This results in the loss of confidentiality, integrity, and availability for the user's system data. Sensitive information such as login credentials, financial details, or personal documents could be exfiltrated, or malware could be installed persistently on the device. The severity is further amplified by the widespread usage of Firefox across enterprise environments where consistent security postures are required to protect corporate assets from web-based attacks.
To mitigate this risk, users must ensure they have updated their browsers to the specified patched versions: Firefox ESR 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17. These releases contain code changes that address the underlying memory management or validation errors in the graphics component. Organizations should enforce automatic update policies to ensure all endpoints are running these secure versions promptly after release. Additionally, deploying browser isolation technologies or content security policies can provide an additional layer of defense by restricting what scripts and resources can interact with the rendering engine. Security teams should also monitor for indicators of compromise related to unusual process creation patterns originating from browser processes, which may indicate attempted exploitation attempts against unpatched systems.
From a classification perspective, this vulnerability aligns with CWE-20 Improper Input Validation or CWE-125 Out-of-bounds Read depending on the specific memory corruption mechanism involved in the graphics stack. It also maps to MITRE ATT&CK technique T1059 Command and Scripting Interpreter if the sandbox escape leads directly to script execution, or more accurately to privilege escalation vectors associated with breaking out of containerized environments like browser sandboxes. Understanding these mappings helps security professionals prioritize remediation efforts based on standard threat models and ensure that defensive measures are aligned with recognized industry frameworks for web application and client-side software security.