CVE-2025-49015 is a vulnerability identified in the Couchbase .NET SDK client library versions prior to 3.7.1. The core issue lies in improper hostname verification during TLS (Transport Layer Security) certificate validation. Specifically, the SDK does not correctly enforce hostname verification, which is a critical step in ensuring that the server's TLS certificate matches the intended hostname, preventing man-in-the-middle (MITM) attacks. Instead of validating hostnames, the SDK uses IP addresses due to a misconfigured default setting that enables an option causing this behavior. This means that when establishing secure connections, the SDK may accept TLS certificates that do not match the expected hostname, potentially allowing attackers to intercept or manipulate encrypted communications. The vulnerability affects the confidentiality and integrity of data transmitted between client applications using the Couchbase .NET SDK and Couchbase servers. Since the SDK is a client library, the vulnerability is exploitable without authentication and does not require user interaction, making it easier for attackers to exploit in environments where network access is possible. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet. The issue was publicly disclosed on June 18, 2025, and fixed in version 3.7.1 of the SDK.

For European organizations, this vulnerability poses a significant risk to the security of applications relying on the Couchbase .NET SDK for database interactions. The improper hostname verification could allow attackers positioned on the network path—such as within compromised internal networks or via external interception—to perform man-in-the-middle attacks. This could lead to unauthorized data disclosure, data tampering, or session hijacking. Organizations in sectors with stringent data protection requirements, such as finance, healthcare, and government, could face regulatory and reputational damage if sensitive data is exposed. Additionally, since Couchbase is often used in enterprise environments for high-performance NoSQL database solutions, the vulnerability could impact critical business applications, potentially disrupting operations or leading to data integrity issues. The lack of authentication requirements for exploitation increases the threat level, especially in environments where network segmentation or encryption is insufficient. However, the absence of known exploits in the wild suggests that immediate widespread attacks are unlikely, but proactive remediation is essential to prevent future exploitation.

To mitigate this vulnerability, organizations should upgrade the Couchbase .NET SDK to version 3.7.1 or later, where proper hostname verification is enforced by default. Until the upgrade can be applied, organizations should review and adjust the SDK configuration to disable the option that causes the use of IP addresses instead of hostnames for TLS verification. Network-level mitigations include enforcing strict TLS inspection policies and ensuring that internal network traffic is segmented and monitored to detect anomalous activities indicative of MITM attacks. Additionally, implementing certificate pinning within client applications can provide an extra layer of defense by ensuring that only trusted certificates are accepted. Organizations should also audit their applications to identify all instances of the Couchbase .NET SDK usage to ensure comprehensive patching. Finally, monitoring network traffic for unusual TLS handshake patterns or certificate anomalies can help detect exploitation attempts early.