CVE-2025-11152 is a recently disclosed vulnerability affecting Mozilla Firefox versions prior to 143.0.3. The flaw exists in the Graphics: Canvas2D component of the browser and is caused by an integer overflow. This type of vulnerability occurs when an arithmetic operation attempts to create a numeric value that exceeds the maximum size the variable can hold, leading to unexpected behavior. In this case, the integer overflow can be exploited to escape the browser's sandbox environment, which is designed to isolate web content and prevent malicious code from affecting the underlying operating system or accessing sensitive resources. By escaping the sandbox, an attacker could potentially execute arbitrary code on the victim's machine with the privileges of the user running Firefox. Although no known exploits are currently reported in the wild, the nature of the vulnerability suggests that it could be leveraged by attackers to compromise user systems via malicious web content or crafted web pages that trigger the overflow in the Canvas2D rendering engine. The lack of a CVSS score indicates that the vulnerability is newly published and has not yet been fully assessed for severity. However, sandbox escapes are generally considered serious because they undermine a fundamental security boundary in modern browsers. The vulnerability affects all Firefox versions prior to 143.0.3, which implies a broad impact given Firefox's widespread use globally. The absence of detailed patch links or exploit indicators suggests that mitigation is primarily through updating to the fixed version once available.

For European organizations, this vulnerability poses a significant risk due to the widespread use of Firefox as a primary web browser in both enterprise and public sectors. Successful exploitation could lead to unauthorized code execution on user endpoints, potentially allowing attackers to install malware, steal sensitive data, or move laterally within corporate networks. Given that the vulnerability enables sandbox escape, it could bypass many existing browser-based security controls, increasing the likelihood of successful attacks. This is particularly concerning for sectors with high-value targets such as finance, government, healthcare, and critical infrastructure, where data confidentiality and system integrity are paramount. Additionally, the vulnerability could be exploited via drive-by downloads or malicious websites, making it a threat vector that does not require user authentication but may require user interaction such as visiting a compromised or malicious site. The potential for widespread impact is heightened by the fact that Firefox is popular in European countries that emphasize open-source software and privacy-focused tools. Organizations relying on Firefox for secure browsing could face increased risk until patches are applied.

European organizations should prioritize updating all Firefox installations to version 143.0.3 or later as soon as the patch becomes available. Until then, organizations can mitigate risk by implementing network-level protections such as web filtering to block access to untrusted or suspicious websites that could host exploit code. Employing endpoint detection and response (EDR) solutions capable of identifying anomalous process behavior related to sandbox escapes can help detect exploitation attempts. Administrators should also enforce strict browser security policies, including disabling unnecessary plugins or extensions that might increase attack surface. User awareness training should emphasize caution when browsing unknown sites or clicking on unsolicited links. Additionally, organizations can consider deploying application sandboxing or virtualization technologies at the OS level to provide an additional containment layer beyond the browser sandbox. Regular vulnerability scanning and asset inventory to identify Firefox versions in use will aid in rapid remediation. Finally, monitoring Mozilla security advisories for updates and patches is critical to maintain timely defenses.