CVE-2026-2767 is a use-after-free vulnerability identified in the WebAssembly component of Mozilla Firefox's JavaScript engine. Use-after-free bugs occur when a program continues to use memory after it has been freed, leading to undefined behavior that attackers can exploit to execute arbitrary code or cause denial of service. This vulnerability affects Firefox versions earlier than 148 and Firefox ESR versions earlier than 140.8. WebAssembly is a low-level bytecode format designed to enable high-performance applications on the web, and its integration into Firefox means that this vulnerability could be triggered by maliciously crafted WebAssembly code embedded in web pages or scripts. The flaw does not require user authentication or interaction beyond visiting a malicious or compromised website, making exploitation relatively straightforward. Although no public exploits have been reported yet, the nature of use-after-free vulnerabilities in browser engines historically leads to rapid exploitation once disclosed. The absence of a CVSS score indicates that the vulnerability is newly published, but the technical details and affected components suggest a high risk. The vulnerability could allow attackers to compromise the browser process, leading to execution of arbitrary code with the privileges of the user running Firefox, potentially enabling further system compromise or data theft.

The impact of CVE-2026-2767 is significant for organizations worldwide that use Firefox as a primary web browser. Successful exploitation could lead to arbitrary code execution, allowing attackers to install malware, steal sensitive information, or disrupt services. This compromises confidentiality, integrity, and availability of affected systems. Since Firefox is widely used in both enterprise and consumer environments, the scope of affected systems is broad. The vulnerability's exploitation does not require user authentication and can be triggered remotely via web content, increasing the risk of widespread attacks. Organizations relying on WebAssembly-based web applications or those in sensitive sectors such as finance, government, and critical infrastructure are particularly vulnerable. The lack of known exploits currently provides a window for proactive mitigation, but the threat of rapid weaponization remains high once exploit code becomes available.

To mitigate CVE-2026-2767, organizations should prioritize updating Mozilla Firefox to version 148 or later, and Firefox ESR to version 140.8 or later as soon as patches are released. Until updates are applied, consider implementing network-level protections such as blocking access to untrusted or suspicious websites that may host malicious WebAssembly content. Employ browser security features like sandboxing and enable strict content security policies (CSP) to limit the execution of untrusted scripts. Monitoring network traffic and endpoint logs for unusual activity related to browser processes can help detect exploitation attempts. Additionally, educate users about the risks of visiting untrusted websites and encourage the use of security-focused browser extensions that can block or restrict WebAssembly execution. Organizations should also maintain an up-to-date inventory of browser versions in use to ensure timely patch deployment and reduce exposure.