CVE-2025-10530 is a security vulnerability identified in the WebAuthn component of Mozilla Firefox for Android, affecting versions prior to Firefox 143. WebAuthn is a web standard used for secure authentication, enabling passwordless logins through public key cryptography. The vulnerability is classified as a spoofing issue, which typically means an attacker could manipulate or falsify authentication data or responses within the WebAuthn process. This could allow an attacker to impersonate a legitimate user or service, potentially bypassing authentication controls. The vulnerability specifically impacts Firefox on Android devices, which use the WebAuthn API to facilitate secure authentication workflows. Although detailed technical specifics such as the exact attack vector or the nature of the spoofing are not provided, the flaw likely involves improper validation or handling of authentication assertions or credentials within the browser's WebAuthn implementation. No CVSS score has been assigned yet, and there are no known exploits in the wild at the time of publication. The vulnerability was published on September 16, 2025, and affects all Firefox versions below 143 on Android. Since WebAuthn is a critical security feature for modern web authentication, a spoofing vulnerability here could undermine the integrity of authentication processes, leading to unauthorized access or session hijacking if exploited.

For European organizations, this vulnerability poses a significant risk especially for those relying on Firefox for Android as a primary browser and utilizing WebAuthn for secure authentication. The spoofing flaw could allow attackers to impersonate legitimate users, potentially gaining unauthorized access to sensitive corporate resources, web applications, or services that depend on WebAuthn for authentication. This could lead to data breaches, unauthorized transactions, or compromise of user accounts. Organizations in sectors such as finance, healthcare, government, and critical infrastructure, where strong authentication is mandatory, could face severe consequences including regulatory penalties under GDPR if personal data is exposed. The impact is heightened in mobile-first or remote work environments where Firefox on Android is commonly used. Additionally, since the vulnerability affects the browser's authentication mechanism, it could facilitate lateral movement within networks if attackers gain initial footholds. The absence of known exploits currently reduces immediate risk but does not eliminate the threat, as attackers may develop exploits once the vulnerability details become widely known.

To mitigate this vulnerability, European organizations should prioritize updating Firefox for Android to version 143 or later as soon as a patch is released by Mozilla. Until an official patch is available, organizations should consider the following specific measures: 1) Temporarily restrict or monitor the use of Firefox for Android for accessing sensitive systems that rely on WebAuthn authentication. 2) Implement multi-factor authentication (MFA) methods that do not solely rely on WebAuthn within critical applications to provide layered security. 3) Increase monitoring and logging of authentication events to detect anomalous or suspicious login attempts that could indicate exploitation attempts. 4) Educate users about the risk and advise them to avoid using Firefox for Android on untrusted networks or devices. 5) Coordinate with IT and security teams to identify and inventory all systems and applications leveraging WebAuthn and assess exposure. 6) Employ endpoint protection and mobile device management (MDM) solutions to enforce browser updates and security policies on Android devices. These targeted actions go beyond generic advice by focusing on the specific affected platform, authentication mechanism, and organizational context.