CVE-2026-76403 in Connect for Kafka
Summary
by MITRE • 08/20/2026
In Splunk Connect for Kafka versions below 2.2.7, an unauthenticated user positioned in the network path could read or alter all relevant data sent from the connector when Kerberos authentication is used with Hypertext Transfer Protocol (HTTP) Event Collector in Splunk Enterprise. The vulnerability is possible because the Kerberos authentication path does not apply the configured certificate validation options when it builds the HTTP client. For more information see Install Splunk Connect for Kafka (https://help.splunk.com/en/data-management/integrate-data-with-add-ons/splunk-connect-for-kafka/2.2/install/install-splunk-connect-for-kafka), Security configurations for Splunk Connect for Kafka (https://help.splunk.com/en/splunk-enterprise/get-data-in/splunk-connect-for-kafka/2.2/configure/security-configurations-for-splunk-connect-for-kafka), and Set up and use HTTP Event Collector with configuration files (https://help.splunk.com/en/splunk-enterprise/get-data-in/get-started-with-getting-data-in/9.4/get-data-with-http-event-collector/set-up-and-use-http-event-collector-with-configuration-files) in the Splunk documentation.
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Analysis
by VulDB Data Team • 08/20/2026
Splunk Connect for Kafka versions prior to 2.2.7 contain a critical security vulnerability that compromises the integrity and confidentiality of data ingestion pipelines when Kerberos authentication is configured alongside the Hypertext Transfer Protocol Event Collector in Splunk Enterprise. This flaw arises from an inconsistency in how the connector handles transport layer security during the establishment of connections with the HTTP Event Collector service. Specifically, while the system is configured to enforce strict certificate validation policies for standard HTTPS communications, this same rigorous validation logic is bypassed when Kerberos authentication is utilized as the primary mechanism for user identity verification. Consequently, the underlying HTTP client constructed by the connector fails to verify the server's digital certificate against trusted certification authorities or validate its hostname and expiration status. This oversight creates a significant gap in the defense-in-depth strategy typically expected from enterprise data ingestion tools, allowing an attacker who is positioned within the network path of the communication channel to intercept, read, or modify all relevant data being transmitted through this specific authentication pathway without detection by standard TLS validation mechanisms.
The technical root cause lies in the implementation details of the Kerberos authentication flow within the Splunk Connect for Kafka component. When a connection request is initiated using Kerberos credentials, the software constructs an HTTP client instance that does not inherit or apply the global certificate validation options defined in the security configuration files. In standard secure configurations, clients are expected to perform mutual verification where both parties prove their identities and ensure they are communicating with legitimate endpoints. By omitting this step during Kerberos-based sessions, the connector effectively operates over an encrypted channel that lacks server-side authentication guarantees. This means that while the data may be encrypted in transit via TLS, the client cannot confirm it is talking to the intended Splunk Enterprise instance rather than a malicious intermediary. An adversary with network-level access can exploit this by performing a man-in-the-middle attack, potentially decrypting sensitive log data or injecting false telemetry events into the SIEM environment if they can also compromise the encryption keys or force protocol downgrades that are not properly restricted due to the missing certificate checks.
The operational impact of this vulnerability is severe for organizations relying on Splunk Connect for Kafka for centralized logging and security monitoring. Since the connector handles high volumes of log data, an attacker could exfiltrate sensitive information such as user credentials, financial records, or proprietary business logic contained within the logs. Furthermore, the ability to alter data allows for sophisticated attacks against the integrity of the security operations center environment. An adversary could inject fabricated events to create noise and distract analysts, delete critical audit trails to cover their tracks, or manipulate log entries to evade detection rules. This undermines the fundamental trust model of the SIEM platform, as administrators can no longer rely on the authenticity of incoming data streams from Kafka topics processed by this connector version. The lack of certificate validation means that even if strong Kerberos authentication is in place for user identity, the server's identity remains unverified, leaving the entire ingestion pipeline vulnerable to spoofing and interception attacks.
To mitigate this risk, organizations must immediately upgrade Splunk Connect for Kafka to version 2.2.7 or later, where the developers have corrected the HTTP client construction logic to ensure that certificate validation options are consistently applied regardless of the authentication method used. Until an upgrade is feasible, administrators should consider network-level controls such as restricting access to the HTTP Event Collector endpoint using firewalls or virtual private networks to limit exposure to trusted subnets only. Additionally, verifying that Kerberos configurations do not inadvertently disable other security features and ensuring that mutual TLS is enforced at a lower infrastructure layer can provide compensating controls. It is also advisable to review Splunk Enterprise documentation regarding secure configuration practices for the HTTP Event Collector to ensure all recommended hardening steps are implemented across the environment. This vulnerability highlights the importance of consistent security policy application across different authentication paths within complex integration tools, ensuring that no single method bypasses fundamental transport layer security checks.