CVE-2024-23689 is a vulnerability classified under CWE-209, involving the generation of error messages that contain sensitive information. It affects multiple ClickHouse client implementations: clickhouse-r2dbc, clickhouse-jdbc, and clickhouse-client, specifically versions earlier than 0.4.6. The flaw arises when these clients are configured to use SSL client certificates with a password-protected private key ('sslkey' parameter). If an exception occurs during database operations—such as a ClickHouseException or SQLException—the exception message logged includes the client certificate password in plaintext. This leakage occurs because the exception handling code inadvertently incorporates sensitive credential data into error messages. The vulnerability is remotely exploitable (AV:N), requires low privileges (PR:L), and no user interaction (UI:N), with an unchanged scope (S:U). The impact is severe, compromising confidentiality (C:H), integrity (I:H), and availability (A:H) of the system. Although no known exploits are reported in the wild yet, the high CVSS score (8.8) reflects the critical nature of the exposure. This vulnerability can lead to unauthorized access to client certificate passwords, potentially enabling attackers to impersonate legitimate clients or decrypt SSL traffic, severely undermining security.

For European organizations, the exposure of client certificate passwords can have significant consequences. Many enterprises and public sector entities rely on ClickHouse for analytics and data warehousing, often transmitting sensitive or regulated data over SSL connections. If attackers gain access to these passwords via logs, they could impersonate clients, intercept or manipulate data, or disrupt services. This compromises data confidentiality, integrity, and availability, potentially violating GDPR and other data protection regulations. The breach of client certificates could also facilitate lateral movement within networks or enable further attacks on critical infrastructure. The impact is particularly acute for sectors handling sensitive personal data, financial information, or critical infrastructure telemetry, making remediation urgent to avoid regulatory penalties and operational disruptions.

The primary mitigation is to upgrade all affected ClickHouse client libraries (clickhouse-r2dbc, clickhouse-jdbc, clickhouse-client) to version 0.4.6 or later, where this vulnerability is fixed. Organizations should audit their usage of SSL client certificates and avoid logging sensitive information in exception messages. Implement strict logging policies that sanitize or redact sensitive data before writing to logs. Additionally, restrict access to logs to authorized personnel only and monitor logs for any suspicious access patterns. Employ network segmentation and strong access controls to limit exposure if credentials are compromised. Regularly review exception handling code in custom integrations to ensure no sensitive data is exposed. Finally, consider rotating client certificate passwords and associated keys if exposure is suspected.