CVE-2026-0885 is a use-after-free vulnerability identified in the JavaScript garbage collection (GC) component of Mozilla Firefox, affecting versions prior to 147 and Firefox ESR versions prior to 140.7. Use-after-free vulnerabilities occur when a program continues to use memory after it has been freed, leading to undefined behavior such as memory corruption, crashes, or arbitrary code execution. In this case, the flaw lies in the GC mechanism responsible for reclaiming unused JavaScript objects, which can be manipulated by an attacker to trigger the use-after-free condition. Exploiting this vulnerability could allow an attacker to execute arbitrary code within the context of the browser, potentially leading to full compromise of the user's system or enabling further attacks such as data theft or malware installation. The vulnerability was published on January 13, 2026, but no CVSS score has been assigned yet, and no known exploits have been reported in the wild. Given Firefox’s extensive use across personal, enterprise, and government environments, the vulnerability poses a significant risk. The absence of a CVSS score suggests that the vulnerability is newly disclosed and under evaluation. The technical details indicate the flaw is specific to the JavaScript GC component, which is critical for browser stability and security. Attackers exploiting this vulnerability would likely need to lure users to malicious web content or compromise legitimate sites to deliver exploit code. The vulnerability affects all platforms where the vulnerable Firefox versions run, including Windows, macOS, and Linux.

For European organizations, this vulnerability poses a substantial risk due to Firefox’s widespread adoption in both private and public sectors. Exploitation could lead to unauthorized code execution, enabling attackers to steal sensitive information, disrupt operations, or deploy malware. Confidentiality could be compromised through data exfiltration, integrity could be undermined by tampering with data or browser behavior, and availability could be affected by crashes or denial-of-service conditions. Critical infrastructure, government agencies, financial institutions, and enterprises relying on Firefox for secure web access are particularly vulnerable. The lack of known exploits currently reduces immediate risk but does not eliminate the threat, as attackers may develop exploits rapidly after disclosure. The vulnerability’s presence in ESR versions, which are commonly used in enterprise environments for stability, increases the potential impact on organizations that delay updates. Overall, the threat could facilitate targeted attacks or widespread exploitation if weaponized, emphasizing the need for timely remediation.

European organizations should immediately prioritize upgrading all Firefox installations to version 147 or later, and Firefox ESR to 140.7 or later, as these versions contain fixes for CVE-2026-0885. Where immediate upgrades are not feasible, organizations should implement compensating controls such as restricting access to untrusted websites, deploying web filtering solutions, and enhancing endpoint detection and response capabilities to identify suspicious browser behavior. Security teams should monitor Mozilla’s security advisories for patch releases and exploit reports. Additionally, organizations should conduct internal audits to inventory Firefox versions in use and enforce update policies. User awareness campaigns should emphasize the risks of visiting untrusted sites and opening suspicious links. Network segmentation and application whitelisting can further reduce exposure. Finally, organizations should prepare incident response plans to address potential exploitation scenarios involving browser vulnerabilities.