CVE-2025-11153 identifies a vulnerability in Mozilla Firefox's JavaScript engine, specifically within the Just-In-Time (JIT) compilation component. The issue arises from a miscompilation during JIT processing, categorized under CWE-94 (Improper Control of Generation of Code). This flaw affects all Firefox versions prior to 143.0.3. The vulnerability allows an attacker to manipulate the JIT compiler's output, potentially leading to unauthorized code execution or modification of the program's intended logic, thereby compromising the integrity of the browser process. The CVSS v3.1 score of 7.5 reflects a high severity, with an attack vector of network (AV:N), low attack complexity (AC:L), no privileges required (PR:N), and no user interaction needed (UI:N). The scope remains unchanged (S:U), and the impact is high on integrity (I:H) but none on confidentiality or availability (C:N/A:N). Exploitation can be achieved remotely by delivering crafted JavaScript code through web pages, making it a potent vector for drive-by attacks or targeted exploitation. Although no exploits have been observed in the wild yet, the vulnerability's characteristics suggest that attackers could develop reliable exploit code. The absence of patch links indicates that updates should be sought directly from Mozilla's official releases. The vulnerability's presence in a widely used browser component underscores the importance of timely remediation to prevent potential compromise of user systems.

For European organizations, the impact of CVE-2025-11153 is significant due to Firefox's widespread use as a primary web browser in both enterprise and public sectors. The vulnerability's ability to compromise browser integrity without requiring user interaction or elevated privileges means attackers can remotely execute malicious code or alter browser behavior simply by enticing users to visit a malicious or compromised website. This can lead to further exploitation such as data tampering, session hijacking, or pivoting into internal networks. Critical sectors including finance, government, healthcare, and energy, which rely heavily on secure web access, could face increased risk of espionage, data breaches, or disruption. The lack of confidentiality and availability impact reduces the risk of data leakage or denial of service directly from this flaw, but the integrity compromise can facilitate more complex attack chains. Additionally, the vulnerability could be leveraged in supply chain attacks or targeted campaigns against high-value European targets. The absence of known exploits currently provides a window for proactive defense, but the threat landscape may evolve rapidly.

European organizations should immediately verify their Firefox versions and upgrade all installations to version 143.0.3 or later, where the vulnerability is patched. Given the lack of direct patch links, administrators should rely on Mozilla's official update channels and verify update integrity via digital signatures. Network-level defenses should be enhanced by implementing web filtering to block access to untrusted or suspicious websites that could host malicious JavaScript. Employing browser security extensions or sandboxing technologies can reduce the impact of potential exploitation. Security teams should monitor browser telemetry and logs for anomalies indicative of JIT miscompilation exploitation attempts. User awareness campaigns should emphasize cautious browsing habits, especially avoiding unknown or suspicious links. For high-risk environments, consider deploying endpoint detection and response (EDR) solutions capable of detecting unusual browser behavior or code injection attempts. Regular vulnerability scanning and penetration testing should include checks for outdated Firefox versions. Finally, maintain close communication with Mozilla security advisories for any updates or emerging exploit reports.