CVE-2026-117972 in Firefox
Summary
by MITRE • 10/27/2026
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 classified as an out-of-bounds write, specifically manifesting through a use-after-free condition within the graphics subsystem of the Mozilla Firefox browser ecosystem. This vulnerability was addressed in version 159 and its extended support release counterpart, version 153.6, marking a significant remediation effort for users relying on these platforms for secure web browsing. The core technical nature of this flaw involves the premature deallocation or invalidation of memory resources that are subsequently accessed by the application logic during rendering operations. In complex graphical environments such as those handled by Firefox's graphics stack, objects representing visual elements must maintain strict lifecycle management to ensure data integrity and prevent unauthorized access to freed memory regions.
From a technical perspective, use-after-free vulnerabilities occur when software continues to utilize pointers or references to memory blocks that have already been released back to the system allocator. In the context of browser rendering engines, this often happens during dynamic updates to page layouts, animations, or hardware-accelerated compositing tasks where multiple threads may interact with shared graphical resources. If the reference counting mechanism fails to properly track active usage before deallocation, or if a race condition allows access after release, the application writes data into memory that is no longer owned by it. This can lead to arbitrary code execution under certain conditions, as an attacker could potentially craft malicious web content designed to exploit this specific timing window and overwrite critical function pointers or object headers within the process space.
The operational impact of such a vulnerability extends beyond simple application instability. While immediate exploitation may result in crashes that degrade user experience through denial of service, sophisticated attackers can leverage these memory corruption errors to bypass modern security mitigations like heap spraying protections or stack canaries. By carefully controlling the contents of the freed memory region before it is reallocated for attacker-controlled data, an adversary can achieve arbitrary read and write primitives within the browser process context. This capability effectively neutralizes sandboxing mechanisms designed to isolate web content from the underlying operating system, potentially allowing full compromise of the user's machine if combined with other vulnerabilities or successful social engineering tactics targeting privilege escalation paths.
Industry standard classifications place this flaw firmly within CWE-416, which defines use-after-free errors as a subset of improper memory handling that leads to undefined behavior and potential security breaches. Furthermore, in terms of tactical execution frameworks such as MITRE ATT&CK, this vulnerability aligns with techniques related to process injection or code execution via browser exploitation chains. The attack vector typically involves delivering malicious HTML, JavaScript, or WebGL content through a compromised website or phishing campaign that triggers the specific rendering path containing the flaw. Defense-in-depth strategies must therefore include not only timely patching but also rigorous static and dynamic analysis of graphics libraries during development to ensure proper reference counting and safe memory deallocation practices are enforced across all code paths involving graphical resource management.
Mitigation for this issue primarily relies on deploying the updated software versions mentioned, which contain patches that enforce stricter validation checks before accessing freed objects or adjust lifecycle management protocols within the graphics engine. Organizations should prioritize updating their Firefox installations to version 159 and ESR 153.6 immediately to close this attack surface. Additionally, implementing browser hardening policies such as disabling unnecessary plugins, enforcing strict content security policies, and utilizing endpoint detection solutions that monitor for anomalous memory access patterns can provide supplementary layers of defense against exploitation attempts targeting known or unknown vulnerabilities in the graphics subsystem.