CVE-2023-39735 in Uomasa_Saiji_news Line
Summary
by MITRE • 10/25/2023
The leakage of the client secret in Uomasa_Saiji_news Line 13.6.1 allows attackers to obtain the channel access token and send crafted broadcast messages.
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Analysis
by VulDB Data Team • 01/26/2026
The vulnerability identified as CVE-2023-39735 represents a critical security flaw in the Uomasa_Saiji_news Line application version 13.6.1 where a client secret has been inadvertently exposed. This exposure creates a significant vector for unauthorized access and privilege escalation within the Line messaging platform ecosystem. The client secret serves as a cryptographic key that authenticates applications to the Line API services, and its leakage fundamentally undermines the security model that protects channel access tokens and other sensitive resources. This vulnerability directly impacts the integrity and confidentiality of communications within the Line platform, particularly affecting applications that rely on proper authentication mechanisms to maintain secure access to their respective channels and user data.
The technical implementation flaw stems from improper handling of authentication credentials within the application's source code or configuration files. When a client secret is exposed, attackers can leverage this information to impersonate legitimate applications and gain unauthorized access to channel access tokens that are typically required for sending broadcast messages and accessing channel management functions. This represents a classic case of credential exposure that aligns with CWE-200, which addresses the exposure of sensitive information to an unauthorized actor. The vulnerability exists at the application level where secure credential management practices have failed to prevent the leakage of authentication materials that should remain confidential and protected from unauthorized access.
The operational impact of this vulnerability extends far beyond simple credential exposure, as it enables attackers to send crafted broadcast messages to all users within the affected channel. This capability provides threat actors with a powerful tool for malicious activities including spam campaigns, phishing attempts, and social engineering attacks that can compromise user trust and platform integrity. The ability to send broadcast messages represents a significant escalation of privileges, as it allows attackers to reach all channel members simultaneously and potentially manipulate or mislead large user bases. This vulnerability directly maps to ATT&CK technique T1566, which covers social engineering tactics through the use of compromised credentials to send malicious communications. The impact on user experience and platform security is severe, as it undermines the trust users place in the messaging service and creates opportunities for large-scale deception and data manipulation.
Mitigation strategies for CVE-2023-39735 require immediate action to revoke and regenerate the compromised client secret, followed by comprehensive security auditing of the application's credential management practices. Organizations should implement robust secret management solutions that prevent hardcoding of credentials in source code and ensure that all authentication materials are properly secured and rotated on regular intervals. The remediation process must include updating the application to remove any exposed secrets from version control systems and implementing automated monitoring for credential leakage. Additionally, security controls should be enhanced to detect unauthorized access attempts and monitor for suspicious broadcast message activities. The vulnerability highlights the importance of following security best practices such as those outlined in NIST SP 800-53, specifically focusing on access control and system and information integrity requirements that mandate proper credential handling and protection. Regular security assessments and penetration testing should be conducted to identify similar exposure vulnerabilities in other applications and ensure that secure coding practices are maintained throughout the software development lifecycle.