CVE-2026-109711 in Firefox
Summary
by MITRE • 10/13/2026
Use-after-free in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox 158 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 within the Mozilla Gecko rendering engine, specifically affecting the Canvas2D API implementation used for dynamic two-dimensional graphics rendering on web pages. This flaw is classified as an out-of-bounds write or use-after-free condition, which falls under CWE-416 in the Common Weakness Enumeration taxonomy. Such vulnerabilities arise when a program continues to use a pointer after it has been freed from memory, leading to undefined behavior that can be exploited by malicious actors. In the context of web browsers, this typically occurs during complex rendering operations where canvas elements are manipulated via JavaScript, particularly when dealing with dynamic content updates or rapid state changes in graphical contexts.
From an operational perspective, this vulnerability allows for arbitrary code execution if a victim is tricked into visiting a specially crafted webpage that triggers the specific sequence of events leading to the memory corruption. The attacker can leverage the use-after-free condition to overwrite adjacent heap data, potentially gaining control over critical program flow or accessing sensitive information stored in memory. This aligns with MITRE ATT&CK technique T1203, which covers Exploitation for Client Execution, as it involves leveraging a software vulnerability to execute code on the target system through social engineering tactics such as phishing links or malicious advertisements. The severity of this issue is heightened by its presence in widely used browser components, making it an attractive target for drive-by download attacks and zero-day exploits targeting enterprise environments that rely heavily on web-based applications.
The fix implemented in Firefox version 158 and the Extended Support Release (ESR) version 153.5 addresses this issue by improving memory safety checks within the Canvas2D rendering pipeline. The patch likely involves ensuring proper lifecycle management of canvas objects, preventing access to freed memory regions during subsequent drawing operations. It may also include enhancements to the garbage collection process or stricter validation of object states before allowing manipulation through JavaScript APIs. These updates are critical for maintaining the integrity of the browser's security model and protecting users from sophisticated web-based attacks that target rendering engines.
To mitigate the risks associated with this vulnerability, organizations should ensure that all instances of Firefox and Firefox ESR are updated to version 158 or later immediately upon availability. For environments using Extended Support Releases, verifying that the build is at least 153.5 is essential to remain protected against known exploits derived from this flaw. Additionally, security teams should monitor for indicators of compromise related to canvas-based attacks and consider implementing content security policies that restrict inline scripts where possible to reduce the attack surface. Regular patch management cycles and automated vulnerability scanning tools can help identify unpatched systems within an enterprise network, ensuring continuous protection against emerging threats targeting browser rendering components.