CVE-2026-109710 in Firefox
Summary
by MITRE • 10/13/2026
Use-after-free in the Graphics: Text component. This vulnerability was fixed in Firefox 158, Firefox ESR 115.43, and Firefox ESR 153.5.
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Analysis
by VulDB Data Team • 10/13/2026
The identified vulnerability represents a critical memory management error classified as an out-of-bounds write resulting from a use-after-free condition within the Graphics Text component of Mozilla Firefox. This specific flaw occurs when the application attempts to access or manipulate memory that has already been deallocated by the system, leading to undefined behavior and potential exploitation scenarios. The issue was addressed in recent security updates including Firefox version 158 as well as extended support releases such as ESR 115.43 and ESR 153.5, indicating a coordinated effort to patch this high-risk defect across both stable and long-term support channels for enterprise environments.
From a technical perspective, use-after-free vulnerabilities arise when pointers are not properly invalidated after memory is freed or when reference counting mechanisms fail to track object lifecycles accurately. In the context of browser rendering engines like Gecko which powers Firefox, the Graphics Text component handles complex operations related to font rendering and text layout optimization. If an attacker can trigger a sequence of events that causes the underlying data structures for text processing to be released while still being referenced by active processes or event handlers, they may gain control over how subsequent memory allocations are interpreted. This misinterpretation allows for arbitrary code execution under the context of the affected application because the browser engine will write data into an unexpected location in memory based on stale pointers.
The operational impact of this vulnerability is severe as it enables remote attackers to execute malicious scripts or binary payloads without user interaction beyond visiting a crafted webpage. By leveraging server-side manipulation of web content, an adversary can construct specific HTML and JavaScript constructs that exploit the race condition inherent in the use-after-free state. Successful exploitation grants full control over the victim's browser process which often leads to complete system compromise since modern browsers operate with elevated privileges relative to standard user applications for performance reasons. This aligns directly with CWE-416 which defines using a pointer after it has been freed, and falls under ATT&CK technique T1203 involving exploitation of client software vulnerabilities where attackers target widely deployed applications to establish initial access or persistence on targeted systems.
Mitigation strategies primarily involve ensuring that all instances of Firefox are updated to the patched versions mentioned above immediately upon availability for production environments. For organizations relying on Extended Support Releases, administrators must verify that their update policies include ESR 153.5 and ESR 115.43 patches which contain the necessary fixes for this memory corruption issue. Additionally implementing strict content security policies can help mitigate some risks by restricting inline script execution and limiting external resource loading thereby reducing the attack surface available to potential exploit developers who rely on injecting malicious code into legitimate pages. Regular auditing of browser configurations against industry standards such as CIS Benchmarks further strengthens defenses against these types of memory corruption attacks ensuring that even if a zero-day were discovered, lateral movement within internal networks would be significantly hindered due to restricted privileges and enhanced monitoring capabilities.