The vulnerability CVE-2026-23529 affects the Aiven-Open BigQuery Connector for Apache Kafka versions prior to 2.11.0. This connector facilitates data streaming from Apache Kafka to Google BigQuery by using Google Cloud credentials for authentication. The flaw lies in the connector's failure to validate externally supplied credential JSON files before processing them with Google authentication libraries. Specifically, an attacker can craft malicious credential configurations containing manipulated credential_source.file paths or credential_source.url endpoints. This manipulation enables arbitrary file reads on the host system or Server-Side Request Forgery (SSRF) attacks, potentially allowing attackers to access sensitive files or internal network resources. The vulnerability requires the attacker to have the ability to configure the connector, implying some level of privilege, but does not require user interaction. The CVSS v3.1 score is 7.7 (high), reflecting network attack vector, low attack complexity, requiring privileges but no user interaction, and a high impact on confidentiality without affecting integrity or availability. No public exploits have been reported yet, but the vulnerability poses a significant risk to organizations relying on this connector for their Kafka to BigQuery data pipelines.

For European organizations, this vulnerability could lead to unauthorized disclosure of sensitive data through arbitrary file reads, potentially exposing credentials, configuration files, or other critical information stored on systems running the vulnerable connector. SSRF exploitation could allow attackers to pivot into internal networks, accessing internal services that are otherwise protected, increasing the risk of further compromise. Organizations handling sensitive or regulated data, such as financial institutions, healthcare providers, and government agencies, face heightened risks of data breaches and compliance violations under GDPR. The disruption of data pipelines could also impact business operations reliant on real-time analytics and reporting. Since the vulnerability requires configuration privileges, insider threats or compromised accounts with such permissions are particularly concerning. The lack of known exploits in the wild suggests a window for proactive mitigation before widespread attacks occur.

The primary mitigation is to upgrade the Aiven-Open BigQuery Connector for Apache Kafka to version 2.11.0 or later, where this vulnerability is addressed. Until upgrading is possible, organizations should enforce strict access controls on who can configure the connector to prevent unauthorized or malicious credential configurations. Implement validation and sanitization of credential JSON files before they are used by the connector, possibly by integrating additional security checks or using hardened credential management processes. Network segmentation and firewall rules should be applied to limit the connector's ability to reach internal resources, reducing SSRF impact. Monitoring and logging of connector configuration changes and authentication attempts can help detect suspicious activity. Additionally, conduct regular security audits of data pipeline components and credential handling practices to identify and remediate potential weaknesses.