CVE-2025-14022 is a vulnerability identified in the LINE client for iOS prior to version 15.4, caused by an integrated financial SDK that improperly handles SSL/TLS certificate validation. The SDK interferes with the application's normal network processing, effectively disabling server certificate verification for a substantial portion of the app's network traffic. This misconfiguration allows a network-adjacent attacker to conduct man-in-the-middle (MitM) attacks by intercepting or modifying encrypted communications between the client and LINE servers. The vulnerability does not require user interaction or authentication, increasing its risk profile. The attack complexity is high, meaning exploitation requires specific conditions or capabilities, but the impact on confidentiality and integrity is severe, as attackers can access or alter sensitive data transmitted over the network. Availability impact is low, as the vulnerability primarily affects data security rather than service continuity. The flaw is specific to iOS LINE client version 15.3 and earlier, with a patch presumably available in version 15.4 or later. No known exploits have been reported in the wild as of the publication date, but the potential for abuse exists, especially given the financial nature of the integrated SDK. The vulnerability was published on December 15, 2025, with a CVSS v3.1 score of 7.7, indicating a high severity level. The issue highlights the risks of third-party SDKs interfering with critical security functions like certificate validation in mobile applications.

For European organizations, this vulnerability poses a significant risk to the confidentiality and integrity of communications conducted via the LINE iOS client, particularly where financial transactions or sensitive data exchanges occur. Attackers positioned on the same network (e.g., public Wi-Fi, corporate networks with insufficient segmentation) could intercept or alter encrypted traffic, potentially leading to data breaches, financial fraud, or unauthorized access to sensitive information. Organizations in sectors such as finance, healthcare, and government that use LINE for communication or integrated financial services are particularly vulnerable. The compromised confidentiality could result in regulatory non-compliance under GDPR due to exposure of personal data. Integrity violations could undermine trust in communications and lead to fraudulent transactions or misinformation. Although availability impact is low, the reputational damage and operational disruptions from data compromise could be substantial. The absence of known exploits in the wild provides a window for proactive mitigation, but the high severity score necessitates urgent attention.

European organizations should immediately verify the LINE client version deployed on iOS devices and ensure all users upgrade to version 15.4 or later where the vulnerability is addressed. Network administrators should enforce strict network segmentation and monitor for unusual traffic patterns indicative of MitM attacks, especially on wireless networks. Employing endpoint protection solutions that can detect SSL/TLS anomalies or suspicious SDK behavior can provide additional defense. Organizations should consider restricting LINE usage on corporate devices until the patch is applied, particularly for users handling sensitive financial data. User education about the risks of using public or unsecured Wi-Fi networks when accessing financial services via mobile apps is critical. Additionally, organizations should review and audit third-party SDK integrations in mobile applications to ensure they do not compromise security controls like certificate validation. Implementing network-level protections such as DNS over HTTPS (DoH) or DNSSEC can reduce the risk of traffic interception. Finally, incident response plans should be updated to include potential MitM attack scenarios involving mobile communication apps.