CVE-2025-5267 is a clickjacking vulnerability identified in Mozilla Firefox and Thunderbird products, specifically affecting Firefox versions earlier than 139 and Firefox ESR versions earlier than 128.11, as well as Thunderbird versions earlier than 139 and ESR versions earlier than 128.11. Clickjacking is a technique where an attacker tricks a user into clicking on something different from what the user perceives, potentially causing unintended actions. In this case, the vulnerability could be exploited by a malicious web page to deceive a user into leaking saved payment card details stored in the browser or email client. The attack vector is remote network-based, requiring no privileges or authentication but necessitating user interaction, such as clicking or interacting with a crafted webpage. The CVSS 3.1 base score is 5.4 (medium), reflecting limited impact on confidentiality and integrity, with no impact on availability. The vulnerability is categorized under CWE-1021, which relates to clickjacking. No patches or exploit code are currently publicly available, and no known exploits have been observed in the wild. The vulnerability affects the confidentiality of sensitive payment information and the integrity of user interactions but does not compromise system availability. The flaw highlights the need for robust browser security mechanisms to prevent UI redressing attacks and protect sensitive stored data. Organizations relying on Firefox and Thunderbird should monitor for official patches and apply them promptly once released.

For European organizations, this vulnerability poses a risk primarily to the confidentiality of sensitive payment card data stored within affected Firefox and Thunderbird versions. Organizations involved in e-commerce, financial services, and any sector handling payment information are particularly vulnerable to data leakage through clickjacking attacks. The integrity of user interactions can also be compromised, potentially leading to unauthorized transactions or data exposure. While the vulnerability does not affect system availability, the leakage of payment data can result in financial loss, reputational damage, and regulatory penalties under GDPR and other data protection laws. The requirement for user interaction limits automated exploitation but does not eliminate risk, especially in environments where users may be targeted via phishing or malicious websites. European organizations with remote or hybrid workforces using outdated browser versions are at increased risk. The absence of known exploits in the wild currently reduces immediate threat but does not preclude future exploitation. Overall, the vulnerability could facilitate targeted attacks against European businesses and consumers, emphasizing the importance of timely mitigation.

1. Monitor Mozilla security advisories closely and apply official patches for Firefox and Thunderbird as soon as they become available to remediate CVE-2025-5267. 2. Until patches are applied, configure browser security settings to enable clickjacking protection features such as X-Frame-Options and Content Security Policy (CSP) frame-ancestors directives where applicable. 3. Deploy endpoint security solutions that can detect and block malicious web content or suspicious user interactions indicative of clickjacking attempts. 4. Educate users about the risks of interacting with untrusted or suspicious websites, emphasizing caution with unexpected prompts or payment-related dialogs. 5. For organizations managing browser deployments, enforce update policies to ensure browsers remain current and unsupported versions are phased out. 6. Consider using browser extensions or security tools that provide additional anti-clickjacking protections. 7. Review and restrict browser-stored payment data where feasible, limiting exposure in case of compromise. 8. Implement network-level web filtering to block access to known malicious domains that could host clickjacking attacks. These measures collectively reduce the attack surface and mitigate the risk of payment data leakage via this vulnerability.