CVE-2025-65830 is a critical security vulnerability identified in a mobile application due to the absence of proper certificate validation during TLS communication. This flaw allows an attacker located upstream—such as on the same network or a compromised router—to perform a man-in-the-middle (MITM) attack by intercepting and decrypting TLS traffic that should otherwise be secure. The attacker can inspect sensitive data transmitted by the app, including authentication tokens and login credentials. The vulnerability is exacerbated by the use of MD5 hashing for login credentials, which is cryptographically weak and susceptible to collision and preimage attacks, potentially allowing attackers to crack the hash and gain unauthorized access. The CVSS 3.1 base score of 9.1 indicates a critical severity with network attack vector, no required privileges or user interaction, and high impact on confidentiality and integrity. The vulnerability is categorized under CWE-295, which relates to improper certificate validation. No patches or fixes are currently published, and no known exploits have been reported in the wild, but the risk remains high due to the ease of exploitation and potential impact. The lack of certificate validation means the app does not verify the authenticity of the TLS server certificate, making it vulnerable to forged certificates and interception. This vulnerability threatens the confidentiality of user data and the integrity of requests, potentially allowing attackers to modify requests in transit and fully compromise user accounts.

For European organizations, this vulnerability poses a significant threat to data confidentiality and user account integrity, especially for those relying on the affected mobile application for sensitive operations or access to corporate resources. The interception and decryption of TLS traffic can lead to exposure of personal data, corporate credentials, and session tokens, violating GDPR requirements and potentially resulting in regulatory penalties. The ability to modify requests in transit can facilitate unauthorized transactions, data manipulation, or privilege escalation. Organizations with mobile workforces or customer-facing mobile apps are particularly vulnerable, as attackers can exploit insecure public or corporate Wi-Fi networks to perform MITM attacks. The compromise of authentication tokens can lead to lateral movement within corporate networks, increasing the risk of broader breaches. The use of MD5 hashing further weakens login security, increasing the likelihood of credential compromise. This vulnerability could also undermine trust in mobile services and damage brand reputation. Critical sectors such as finance, healthcare, and government services in Europe could face severe operational and reputational impacts if exploited.

Immediate mitigation should focus on implementing strict certificate validation within the mobile application, ensuring that the app verifies the server's TLS certificate against trusted certificate authorities and rejects invalid or self-signed certificates. Developers should replace MD5 hashing with a secure, modern hashing algorithm such as bcrypt, Argon2, or SHA-256 with salt to protect login credentials. Employ certificate pinning to bind the app to specific certificates or public keys, reducing the risk of MITM attacks. Network traffic should be monitored for anomalies indicative of interception or modification attempts. Organizations should educate users about the risks of using unsecured Wi-Fi networks and encourage the use of VPNs for mobile connections. Incident response plans should include procedures for detecting and responding to token theft or account compromise. Regular security assessments and penetration testing of the mobile app should be conducted to identify and remediate similar weaknesses. Finally, vendors must prioritize releasing patches or updates to address this vulnerability promptly and communicate the urgency to their user base.