CVE-2026-117985 in Firefox
Summary
by MITRE • 10/27/2026
Sandbox escape due to use-after-free in the Graphics component. This vulnerability was fixed in Firefox 159 and Firefox ESR 153.6.
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Analysis
by VulDB Data Team • 10/27/2026
The identified security flaw represents a critical memory management error within the Mozilla Firefox graphics subsystem, specifically categorized as an out-of-bounds write resulting from a use-after-free condition. In software engineering terms, this vulnerability arises when the application continues to reference a block of memory after it has been freed or deallocated by the system. This scenario typically occurs in complex rendering engines where objects representing graphical elements are dynamically created and destroyed during page loading or animation processes. When an object is deleted but pointers to that object remain active within other data structures, subsequent operations may inadvertently write to the now-invalid memory location. In the context of graphics processing, this often involves texture buffers, canvas contexts, or WebGL resources where precise memory alignment and lifecycle management are paramount for stability and security.
From a technical perspective, an out-of-bounds write allows malicious actors to corrupt adjacent memory structures, potentially overwriting function pointers, object headers, or other critical data fields within the process address space. This corruption can lead to arbitrary code execution if the attacker can carefully craft input that manipulates these overwritten values to redirect control flow to shellcode injected into the heap or stack. The graphics component is particularly susceptible because it handles untrusted content from web pages, making it a prime target for exploitation via malicious HTML, CSS, JavaScript, or embedded media files. The severity of this vulnerability lies in its potential to bypass standard browser sandboxing mechanisms, allowing an attacker to escape the restricted environment and gain higher privileges on the host system.
The operational impact of such a flaw is severe, as it enables remote code execution through simple web page visits without requiring user interaction beyond loading the malicious content. Attackers can leverage this vulnerability to install malware, steal sensitive data such as cookies or session tokens, or establish persistent backdoors within the victim's environment. Since graphics rendering occurs frequently and often in background tabs or hidden frames, the attack surface is broad. Users browsing compromised websites or visiting sites with injected ads could trigger the exploit silently. The lack of immediate user consent for memory manipulation makes this a high-risk vector for drive-by download attacks and advanced persistent threats targeting enterprise environments where Firefox is widely deployed.
Mitigation strategies primarily involve applying the vendor-provided patches that address the underlying memory management logic in the graphics engine. For organizations, it is imperative to enforce automated update policies to ensure all endpoints are running Firefox version 159 or later, as well as the Extended Support Release (ESR) version 153.6 or newer. These updates contain specific code changes that validate object lifecycles and prevent access to freed memory regions. Additionally, deploying browser isolation technologies such as Microsoft Edge IE Mode alternatives or dedicated sandboxing solutions can limit the blast radius if a vulnerability is exploited before patching occurs. Security teams should also monitor for indicators of compromise related to unusual process behavior in graphics-related subsystems and ensure that exploit mitigation techniques like Data Execution Prevention (DEP) and Address Space Layout Randomization (ASLR) are enabled at the operating system level to increase the difficulty of successful exploitation.
This vulnerability aligns with Common Weakness Enumeration identifier CWE-416, which describes use-after-free errors, a category known for its high exploitability due to the deterministic nature of memory corruption when properly crafted. In terms of tactical classification under MITRE ATT&CK, this falls under Tactic TA0002 Execution and Technique T1059 Command and Scripting Interpreter if used in conjunction with script-based delivery mechanisms, or more broadly within Initial Access vectors that leverage browser vulnerabilities for code execution. The fix emphasizes the importance of rigorous memory safety practices in high-performance components like graphics engines, where performance optimizations sometimes conflict with strict security boundaries. Continuous monitoring and rapid patch deployment remain the most effective defenses against such zero-day style exploits until broader architectural shifts toward memory-safe languages are fully implemented across the browser's core infrastructure.