CVE-2025-20381 affects Splunk MCP Server versions below 0.2.4 and involves an authorization bypass vulnerability in the Model Context Protocol (MCP) tool named run_splunk_query. The vulnerability arises because the software performs an authorization check when an actor attempts to access a resource or perform an action but does not correctly enforce it. Specifically, attackers with access to the MCP tool can embed SPL (Search Processing Language) commands as sub-searches, effectively bypassing the SPL command allowlist controls intended to restrict the scope of queries. This allows unauthorized execution of SPL commands beyond the intended restrictions, potentially leading to unauthorized data access, data integrity compromise, or denial of service conditions. The vulnerability has a CVSS 3.1 base score of 5.4, indicating medium severity, with an attack vector of network (AV:N), low attack complexity (AC:L), requiring privileges (PR:L), no user interaction (UI:N), unchanged scope (S:U), no confidentiality impact (C:N), but with integrity (I:L) and availability (A:L) impacts. No known exploits are currently reported in the wild. The vulnerability was published on December 3, 2025, and affects specifically version 0.2 of the Splunk MCP Server app. The root cause is insufficient validation of embedded SPL commands within sub-searches, allowing privilege escalation within the MCP tool's query execution context.

For European organizations, this vulnerability could lead to unauthorized execution of SPL queries that bypass intended access controls, potentially exposing sensitive operational data or allowing manipulation of data integrity within Splunk environments. This could disrupt security monitoring, incident response, and business intelligence processes that rely on accurate and authorized Splunk queries. The availability impact could manifest as denial of service if malicious queries consume excessive resources or cause application instability. Organizations in sectors such as finance, telecommunications, energy, and government, which heavily rely on Splunk for security analytics and operational intelligence, may face increased risk of data manipulation or service disruption. The medium severity rating reflects moderate risk but should not be underestimated given the critical role of Splunk in security operations centers (SOCs).

1. Upgrade the Splunk MCP Server app to version 0.2.4 or later, where the authorization bypass issue is fixed. 2. Restrict access to the run_splunk_query MCP tool strictly to trusted administrators or service accounts with a legitimate need. 3. Implement monitoring and alerting on unusual or complex SPL queries, especially those involving sub-searches, to detect potential exploitation attempts. 4. Conduct regular audits of MCP tool usage and access logs to identify unauthorized or anomalous activity. 5. Apply network segmentation and firewall rules to limit exposure of Splunk MCP Server interfaces to only trusted internal networks. 6. Educate Splunk administrators and security teams about this vulnerability and ensure timely patch management. 7. Consider deploying application-layer controls or query whitelisting mechanisms if supported, to further restrict SPL command execution scope.