CVE-2026-117937 in Firefox
Summary
by MITRE • 10/27/2026
Invalid pointer in the JavaScript Engine component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, and Firefox ESR 153.6.
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Analysis
by VulDB Data Team • 10/27/2026
The identified security flaw resides within the JavaScript engine of Mozilla Firefox, specifically involving an invalid pointer dereference that can lead to memory corruption. This type of vulnerability typically arises when the runtime environment attempts to access a memory address that has not been properly allocated or has already been freed by the garbage collector. In complex web applications where dynamic script execution is frequent, such errors in the underlying engine can result in undefined behavior, potentially allowing an attacker to execute arbitrary code with the privileges of the victim user if exploited successfully. The issue highlights the inherent risks associated with low-level memory management within high-performance scripting engines that must balance speed and safety through complex optimization layers.
From a technical perspective, this vulnerability falls under the category of improper input validation leading to invalid pointer usage, which is commonly classified under CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer or more specifically CWE-416 Use After Free if the pointer references deallocated memory. The attack vector likely involves crafting malicious JavaScript code that triggers specific edge cases in the Just-In-Time compiler or garbage collection routines, causing the engine to lose track of valid memory regions. When such conditions are met during normal browsing activity, particularly on untrusted websites designed to exploit these timing windows, it can lead to a crash or potentially more severe consequences depending on the exact state of the heap at the moment of exploitation.
The operational impact of this vulnerability is significant for users who rely on Firefox for accessing sensitive online services such as banking portals, email clients, and enterprise applications. An attacker could leverage this flaw through a web-based attack vector to compromise the integrity of the browsing session. While modern browsers employ various mitigations like sandboxing and ASLR that raise the bar for successful exploitation, any memory corruption bug remains a critical risk because it can potentially be chained with other vulnerabilities to achieve full system compromise or privilege escalation within the browser process context. The severity is further amplified by the widespread adoption of Firefox across both desktop and enterprise environments where consistent security posture is mandatory.
To mitigate this risk, users must ensure they are running versions of Firefox that include the specific patch for this issue, which includes Firefox 159 as well as the Extended Support Release versions 115.44 and 153.6. Organizations should prioritize updating their fleet to these patched releases immediately to close the window of exposure. Additionally, implementing strict content security policies can help limit the impact of any potential script execution by restricting sources from which scripts are allowed to load. Regular monitoring for browser updates and enforcing automated patch management processes are essential practices in maintaining a robust defense against such engine-level vulnerabilities that target core components rather than just application-layer features.