CVE-2025-13018 is a vulnerability identified in Mozilla Firefox's DOM security component that allows an attacker to bypass existing mitigations designed to protect the Document Object Model (DOM). This flaw affects Firefox versions earlier than 145 and Firefox ESR versions earlier than 140.5. The DOM is a critical browser component responsible for representing and interacting with web page content. A mitigation bypass here means that security controls intended to prevent unauthorized access or manipulation of DOM elements can be circumvented, potentially allowing malicious web content to access or alter sensitive information. The CVSS 3.1 base score of 8.1 reflects a high severity, with the vector indicating network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), but user interaction is necessary (UI:R). The scope remains unchanged (S:U), but the impact on confidentiality and integrity is high (C:H/I:H), while availability is not affected (A:N). This suggests that an attacker can remotely exploit this vulnerability by tricking a user into visiting a malicious or compromised website, leading to unauthorized disclosure or modification of data within the browser context. There are no known exploits in the wild at the time of publication, and no patches have been linked yet, indicating that the vulnerability is newly disclosed. The CWE-288 classification points to an authentication bypass or similar security control bypass issue. Given Firefox's widespread use, especially in Europe, this vulnerability represents a significant risk vector for data confidentiality and integrity breaches.

For European organizations, the impact of CVE-2025-13018 could be substantial, particularly for those relying heavily on Firefox for web access to sensitive internal or cloud-based applications. The vulnerability enables attackers to bypass DOM security mitigations, potentially exposing confidential data such as credentials, personal information, or proprietary business data. This could lead to data breaches, intellectual property theft, or unauthorized data manipulation. Since the attack requires user interaction, phishing or social engineering campaigns could be leveraged to exploit this vulnerability. The lack of availability impact means systems remain operational, but the integrity and confidentiality risks could undermine trust and compliance with regulations such as GDPR. Organizations in sectors like finance, government, healthcare, and critical infrastructure are especially at risk due to the sensitivity of their data and the regulatory environment in Europe. The absence of known exploits currently provides a window for proactive mitigation before widespread exploitation occurs.

1. Monitor Mozilla security advisories closely for the release of patches addressing CVE-2025-13018 and apply updates to Firefox and Firefox ESR as soon as they become available. 2. Until patches are released, consider deploying browser security policies that restrict or disable JavaScript execution on untrusted or unknown websites using Content Security Policy (CSP) or browser extensions. 3. Educate users about the risks of interacting with suspicious links or websites, emphasizing caution with unsolicited emails or messages that could lead to malicious sites. 4. Employ network-level web filtering to block access to known malicious domains and URLs that could host exploit code. 5. Use endpoint detection and response (EDR) tools to monitor for unusual browser behaviors indicative of exploitation attempts. 6. For high-risk environments, consider temporarily restricting Firefox usage or using alternative browsers with unaffected versions until patches are applied. 7. Implement multi-factor authentication (MFA) on critical systems to reduce the impact of credential theft resulting from browser-based attacks. 8. Regularly review and update incident response plans to include scenarios involving browser-based DOM security bypasses.