CVE-2024-8381 in Firefox
Summary
by MITRE • 09/03/2024
A potentially exploitable type confusion could be triggered when looking up a property name on an object being used as the `with` environment. This vulnerability affects Firefox < 130, Firefox ESR < 128.2, and Firefox ESR < 115.15.
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Analysis
by VulDB Data Team • 11/05/2025
This vulnerability represents a critical type confusion flaw in the JavaScript engine of Mozilla Firefox browsers, specifically impacting versions prior to 130 for regular releases and 128.2 and 115.15 for extended support releases. The issue manifests when the engine processes property lookups on objects that are functioning as `with` environment contexts, creating a scenario where the runtime incorrectly handles type information during object property resolution. The underlying technical mechanism involves the JavaScript engine's inability to properly distinguish between different object types when they are used within the `with` statement context, leading to memory corruption and potential code execution opportunities. This type confusion vulnerability falls under the CWE-843 category, which specifically addresses the use of objects of the wrong type, and represents a significant deviation from proper type safety mechanisms within the engine's memory management.
The operational impact of this vulnerability extends beyond simple browser instability, as it creates a pathway for remote code execution when an attacker can control the object types being manipulated within a `with` environment. The `with` statement in JavaScript creates a special execution context where property lookups are resolved against the specified object, and when combined with the type confusion mechanism, it allows attackers to manipulate memory layout in ways that could lead to arbitrary code execution. This vulnerability is particularly concerning because it can be triggered through web content without requiring user interaction, making it a prime candidate for drive-by attacks. The attack surface includes web applications that utilize `with` statements or dynamic property access patterns that could be manipulated by malicious actors to exploit the type confusion.
Mitigation strategies should focus on immediate browser updates to versions containing the patched JavaScript engine, as this vulnerability directly relates to the engine's memory management and type handling mechanisms. Organizations should implement browser hardening measures including disabling unnecessary JavaScript features, employing content security policies, and monitoring for suspicious web activity that might indicate exploitation attempts. The vulnerability's relationship to the ATT&CK framework places it within the technique category of "Exploitation for Client Execution" and potentially "Memory Injection" techniques, as attackers would leverage the type confusion to inject and execute malicious code within the browser process. Network security controls should include web application firewalls that can detect and block suspicious JavaScript patterns, particularly those involving `with` statements or dynamic object manipulation that could trigger the vulnerability conditions.