CVE-2025-14021 is a vulnerability in the in-app browser component of the LINE client for iOS, specifically affecting versions prior to 14.14, including version 14.13. The vulnerability allows an attacker to perform address bar spoofing by injecting malicious JavaScript into iframes rendered within the in-app browser. This malicious script can manipulate the displayed URL in the address bar, making it appear as a trusted or legitimate site while actually showing attacker-controlled content. This spoofing enables phishing attacks by overlaying malicious content that deceives users into divulging sensitive information such as credentials or personal data. The vulnerability is categorized under CWE-451, which relates to address bar spoofing issues that undermine user trust in the authenticity of the displayed URL. The attack vector is remote network-based (AV:N), requires low attack complexity (AC:L), no privileges (PR:N), but does require user interaction (UI:R). The scope is unchanged (S:U), with no direct impact on confidentiality (C:N), but a low impact on integrity (I:L) and no impact on availability (A:N). No patches or exploits are currently publicly available, but the vendor has released version 14.14 to address the issue. The vulnerability is significant because LINE is widely used for personal and business communication, and the in-app browser is a common attack surface for phishing and social engineering. By exploiting this flaw, attackers can bypass URL verification mechanisms that users rely on to confirm site legitimacy, increasing the risk of successful phishing campaigns.

For European organizations, the impact of CVE-2025-14021 lies primarily in the potential for phishing attacks that could lead to credential theft, unauthorized access, and subsequent compromise of corporate accounts or sensitive information. Since LINE is popular in several European countries for both personal and professional communication, employees using vulnerable versions of the iOS client may be targeted by attackers leveraging this spoofing vulnerability. This could facilitate spear-phishing campaigns that bypass traditional email filters by exploiting trusted communication channels. The integrity of user interactions is compromised, potentially leading to financial fraud, data breaches, or lateral movement within corporate networks if attackers gain access to internal systems. Although the vulnerability does not directly affect confidentiality or availability, the indirect consequences of successful phishing can be severe. Organizations with BYOD policies or those that rely on LINE for customer engagement should be particularly vigilant. The lack of known exploits in the wild reduces immediate risk but does not eliminate the threat, especially as attackers often weaponize such vulnerabilities once publicly disclosed.

The primary mitigation is to update the LINE client for iOS to version 14.14 or later, where the vulnerability has been addressed. Organizations should enforce mobile device management (MDM) policies that mandate timely application updates for corporate and BYOD devices. User education is critical: train employees to recognize phishing attempts, especially those originating from in-app browsers, and to verify URLs through external browsers when in doubt. Implement network-level protections such as DNS filtering and web proxies that can detect and block known phishing domains. Consider disabling or restricting the use of in-app browsers within LINE if feasible, or use security solutions that monitor app behavior for suspicious activity. Regularly audit and monitor for unusual login patterns or access attempts that could indicate credential compromise stemming from phishing. Finally, maintain an incident response plan that includes steps for addressing phishing incidents originating from mobile applications.