CVE-2026-76348 in Splunk
Summary
by MITRE • 08/20/2026
In Splunk Enterprise versions below 10.4.2, 10.2.6, 10.0.9, and 9.4.14, a user who holds a Splunk role that contains the high-privilege list_search_head_clustering capability could send a read request to Search Head Cluster member control endpoints and change cluster state, which could allow for a denial of service. The vulnerability is possible because the Search Head Cluster member control endpoints do not require a state-changing Hypertext Transfer Protocol (HTTP) request type before they apply read-only authorization.
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Analysis
by VulDB Data Team • 08/20/2026
The identified vulnerability in Splunk Enterprise versions prior to 10.4.2, 10.2.6, 10.0.9, and 9.4.14 represents a critical authentication bypass within the Search Head Cluster management infrastructure. The flaw stems from an improper implementation of access control mechanisms on specific internal endpoints designed for cluster member communication. Specifically, these endpoints handle state-changing operations but fail to enforce strict validation of the Hypertext Transfer Protocol request method before applying authorization checks. This architectural oversight allows users with roles containing the high-privilege list_search_head_clustering capability to manipulate cluster states by sending read requests that are interpreted as write or state-modifying actions due to the lack of method-based filtering in the security logic.
From a technical perspective, this issue is classified under CWE-284 Improper Access Control and aligns with MITRE ATT&CK technique T1078 Valid Accounts when leveraged by an insider threat or compromised account holder who possesses legitimate but overly permissive roles. The core defect lies in the server-side processing of HTTP requests where the authorization module checks for permissions based on user role attributes without verifying that the incoming request method matches the expected operation type for those permissions. Consequently, a GET request intended for reading cluster status can be processed as if it were a POST or PUT request designed to alter configuration or state, effectively bypassing the intended separation of duties between read-only and administrative functions within the clustering subsystem.
The operational impact of this vulnerability is significant, primarily manifesting as a denial of service against the Splunk Search Head Cluster. By exploiting this flaw, an authenticated user can force cluster members into invalid states, disrupt leader election processes, or cause synchronization failures among nodes. This disruption prevents legitimate users from performing searches and analytics, effectively rendering the security information and event management platform unusable for its intended purpose. In high-availability environments where continuous log ingestion and real-time threat detection are critical, such a denial of service can lead to substantial gaps in visibility and potential compliance violations due to data processing interruptions.
Mitigation strategies must prioritize immediate patching to the latest stable release that addresses this specific access control logic error. Administrators should upgrade Splunk Enterprise to version 10.4.2 or later, where the endpoint handling has been corrected to strictly validate HTTP methods against authorized operations before proceeding with state changes. In environments where immediate patching is not feasible due to operational constraints, network-level controls such as firewall rules restricting access to cluster management ports from untrusted subnets can provide a temporary compensating control. Additionally, reviewing and tightening Splunk roles by removing the list_search_head_clustering capability from users who do not strictly require it for their job functions will reduce the attack surface available to potential adversaries seeking to exploit this misconfiguration.