CVE-2026-2796 identifies a vulnerability in Mozilla Firefox's JavaScript engine, specifically within the WebAssembly component's Just-In-Time (JIT) compiler. The issue arises from a miscompilation during JIT optimization, where the generated machine code does not correctly represent the intended WebAssembly instructions. This can lead to incorrect program behavior, potentially allowing attackers to manipulate execution flow or cause memory corruption. Since WebAssembly is designed to run high-performance code within the browser, this vulnerability could be exploited by malicious web pages or scripts to bypass security boundaries, execute arbitrary code, or escalate privileges within the browser context. The vulnerability affects all Firefox versions prior to 148, although the exact affected versions are unspecified. No public exploits have been reported yet, but the nature of JIT miscompilation vulnerabilities historically presents significant risk due to their potential for remote exploitation without requiring prior authentication. The lack of a CVSS score indicates that the severity assessment must consider the technical impact and exploitation complexity. Mozilla has published the vulnerability but has not yet released patches or detailed mitigations, emphasizing the need for vigilance. The vulnerability highlights the risks inherent in complex JIT compilation processes, especially in components like WebAssembly that handle low-level code execution within browsers.

If exploited, this vulnerability could allow attackers to execute arbitrary code or manipulate browser behavior, compromising confidentiality, integrity, and availability of user data and browser processes. This could lead to unauthorized access to sensitive information, session hijacking, or persistent browser compromise. Organizations relying on Firefox for secure web access could face data breaches or targeted attacks, especially if users visit malicious or compromised websites hosting crafted WebAssembly content. The vulnerability's exploitation could also undermine trust in browser security and disrupt normal operations. Since Firefox is widely used across enterprises, governments, and consumers globally, the potential impact is significant. The absence of known exploits currently reduces immediate risk, but the vulnerability remains a critical concern due to the ease of remote exploitation via web content and the broad attack surface presented by WebAssembly. The impact is amplified in environments where Firefox is used to access sensitive or critical web applications.

Organizations and users should upgrade to Firefox version 148 or later as soon as patches become available to address this vulnerability. Until patches are released, consider disabling or restricting WebAssembly execution in Firefox via browser settings or enterprise policies to reduce exposure. Employ browser sandboxing and isolation techniques to limit the impact of potential exploitation. Monitor network traffic and browser behavior for anomalies indicative of exploitation attempts involving WebAssembly. Educate users about the risks of visiting untrusted websites that might host malicious WebAssembly code. Implement web content filtering to block or restrict access to suspicious domains. Maintain up-to-date endpoint protection solutions capable of detecting exploitation attempts. Coordinate with Mozilla security advisories for timely updates and apply security patches promptly. For high-security environments, consider alternative browsers or hardened configurations that limit JIT compilation features until the vulnerability is resolved.