CVE-2026-92034 in Firefox
Summary
by MITRE • 09/15/2026
Site isolation issue in the Graphics component. This vulnerability was fixed in Firefox 156.
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Analysis
by VulDB Data Team • 09/15/2026
The identified site isolation flaw within the Mozilla Firefox graphics subsystem represents a critical breach of browser security architecture, specifically targeting the mechanism designed to separate content from different origins into distinct processes or memory spaces. Site isolation is a fundamental defense-in-depth strategy employed by modern web browsers to prevent cross-site attacks such as Spectre-style side-channel exploits and data leakage between tabs belonging to different domains. By enforcing strict boundaries where each site runs in its own isolated process, the browser ensures that malicious scripts from one origin cannot access sensitive memory or state information associated with another origin. The vulnerability described indicates a failure in this enforcement mechanism within the graphics component, which is responsible for rendering visual content and handling GPU interactions. When site isolation fails at this level, it effectively nullifies the protective barrier intended to contain potential exploits within their respective sandboxed environments, thereby allowing an attacker who has successfully executed arbitrary code on one website to potentially influence or read data from another unrelated website that shares the same underlying graphics resources or process boundaries.
From a technical perspective, this flaw likely stems from improper handling of context switching, resource allocation, or state management within the rendering pipeline when multiple sites are active simultaneously. Graphics components often maintain shared states for performance optimization, such as caching textures, managing shader programs, or retaining GPU command buffers. If these resources are not correctly segregated by origin identifier during creation and usage phases, a malicious site could exploit this overlap to infer information about another tab through timing attacks or direct memory access if the isolation boundary is bypassed via race conditions or logic errors in the graphics API implementation. This type of vulnerability aligns with CWE-200, which classifies it as an Information Exposure Vulnerability, and more specifically relates to CWE-16 regarding platform-specific configuration issues where security controls are not correctly applied due to architectural oversights. Furthermore, this flaw facilitates techniques categorized under MITRE ATT&CK ID T1537, which involves transferring data from a victim system through the destination of an exfiltration attack by leveraging shared resources or side channels that were intended to be isolated.
The operational impact of such a vulnerability is severe because it undermines one of the most effective defenses against sophisticated web-based attacks. An attacker could potentially use this flaw to perform cross-site timing attacks, where they measure how long certain graphics operations take on their malicious page compared to those on a target victim site, thereby deducing sensitive information like passwords or session tokens based on variations in rendering times caused by different data states. Additionally, if the isolation failure allows for memory corruption primitives across process boundaries, it could lead to arbitrary code execution with higher privileges than intended, effectively breaking out of the browser sandbox entirely. This compromises not only user privacy but also system integrity, as a successful exploit could serve as an initial vector for further lateral movement or persistent access on the victim's machine. The severity is amplified by the fact that graphics rendering occurs frequently and continuously during normal browsing activity, providing ample opportunities for exploitation without requiring complex social engineering beyond hosting malicious content on a website visited by the user.
Mitigation strategies primarily rely on applying the vendor-provided patch available in Firefox version 156 or later, which addresses the underlying logic errors in the graphics subsystem's site isolation enforcement. Users and organizations should ensure that browsers are updated promptly to maintain these critical security boundaries. In environments where immediate patching is not feasible, network-level controls such as strict Content Security Policy headers can help limit the types of scripts and resources loaded from untrusted origins, reducing the attack surface available for exploitation. Additionally, enabling enhanced tracking protection features may restrict access to certain third-party graphics APIs that are often targeted in these scenarios. Long-term resilience requires continuous auditing of browser rendering engines against evolving threat models, particularly focusing on how shared hardware accelerators manage context isolation and ensuring that security checks are performed at every stage of resource lifecycle management rather than relying solely on initial process creation boundaries.