Summary
CVE-2026-76402 is a Server-Side Request Forgery (CWE-918) vulnerability in Splunk Connect for Kafka that allows an unauthenticated actor with access to the Kafka Connect REST API to configure an insecure HTTP Event Collector (HEC) endpoint. Because the connector does not enforce secure transport validation for the configured HEC endpoint by default, this can cause the connector to transmit Splunk authentication credentials (HEC tokens) to an attacker-controlled server. The issue carries a CVSS v3.1 base score of 8.2 (High).
Technical details
- Root cause: The connector’s HTTP Event Collector endpoint validation logic does not require secure transport (e.g., TLS/HTTPS enforcement) by default when a connector configuration is applied.
- Trigger conditions: An attacker who can reach the Kafka Connect REST API (which manages Splunk Connect for Kafka connector configurations) can submit or modify a connector configuration to point the HEC endpoint at a server they control.
- Attack vector: Network — exploitation requires network access to the Kafka Connect REST API but does not require prior authentication to Splunk itself (PR:N, UI:N per the CVSS vector).
- Impact: Once the malicious HEC endpoint is configured, the connector transmits HEC authentication credentials (tokens) to the attacker-controlled destination, resulting in high confidentiality impact (credential/token disclosure). The advisory also notes limited event delivery manipulation is possible (low integrity impact), while availability is not affected.
Affected software
- Splunk Connect for Kafka versions 2.2 through 2.2.6 (fixed in 2.2.7)
Severity
- CVSS v3.1 Base Score: 8.2 (High)
- Vector String:
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
Mitigation and recommended actions
- Immediate: Upgrade Splunk Connect for Kafka to version 2.2.7 or later, which enforces secure transport validation for HEC endpoint configuration.
- If immediate patching is not possible:
- Restrict network access to the Kafka Connect REST API to trusted administrative hosts only, since exploitation depends on reachability of this API.
- Audit existing Kafka Connect connector configurations for Splunk Connect for Kafka to confirm the configured HEC endpoint uses HTTPS and points to a legitimate, expected Splunk HEC destination.
- Rotate any HEC tokens that may have been exposed to an unexpected or attacker-controlled endpoint.
- Apply network-layer egress controls to prevent the Kafka Connect host from sending outbound HEC traffic to unapproved destinations.

