CVE-2025-20370 Overview
CVE-2025-20370 affects Splunk Enterprise and Splunk Cloud Platform. An authenticated user holding a role with the change_authentication capability can issue multiple Lightweight Directory Access Protocol (LDAP) bind requests to a specific internal endpoint. The repeated requests drive server CPU usage to levels that cause a denial of service (DoS) until the instance restarts. The flaw maps to [CWE-400] (Uncontrolled Resource Consumption) and [CWE-770] (Allocation of Resources Without Limits or Throttling). Exploitation requires high-privilege access, which limits the attacker population but still exposes platforms where administrative roles are widely distributed.
Critical Impact
An authenticated administrator with change_authentication can exhaust CPU resources on a Splunk Enterprise instance and force a service restart to recover.
Affected Products
- Splunk Enterprise versions below 10.0.1, 9.4.4, 9.3.6, and 9.2.8
- Splunk Cloud Platform versions below 9.3.2411.108, 9.3.2408.118, and 9.2.2406.123
- Deployments where non-administrative roles inherit the change_authentication capability
Discovery Timeline
- 2025-10-01 - CVE-2025-20370 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-20370
Vulnerability Analysis
Splunk Enterprise exposes an internal endpoint used by the LDAP authentication scheme configuration workflow. The endpoint processes LDAP bind requests without enforcing rate limiting or concurrency controls. A user who sends repeated bind requests triggers sustained CPU consumption on the Splunk server. The condition persists until an administrator restarts the Splunk Enterprise instance, interrupting search, ingestion, and alerting workloads for the duration of the outage.
The attack requires the change_authentication capability, a high-privilege role component that governs authentication scheme management. Any custom role that inherits this capability inherits the ability to trigger the DoS. Splunk documents role capability assignment in its capability reference.
Root Cause
The underlying defect is uncontrolled resource consumption in the LDAP bind handler. The endpoint accepts an unbounded number of bind operations per authenticated session, and each operation performs CPU-intensive work. Without throttling, request queueing, or concurrency caps, repeated submissions scale CPU usage linearly until the host becomes unresponsive.
Attack Vector
The attack vector is network-based and requires valid credentials for a role that includes change_authentication. The attacker authenticates to Splunk Web or the REST API, then submits repeated LDAP bind requests to the internal endpoint used by the LDAP configuration flow. No user interaction is required beyond the authenticated session. Confidentiality and integrity are not impacted; the outcome is availability loss.
No public proof-of-concept exploit is referenced in the advisory. See the vendor advisory for configuration guidance: Splunk Security Advisory SVD-2025-1005.
Detection Methods for CVE-2025-20370
Indicators of Compromise
- Sustained high CPU utilization on splunkd processes without a corresponding search or ingestion workload.
- Clusters of LDAP bind requests originating from a single authenticated user session targeting the LDAP configuration endpoint.
- Unexpected Splunk Enterprise service restarts initiated by administrators to recover responsiveness.
Detection Strategies
- Audit role assignments to identify every user and role granted the change_authentication capability, and correlate activity from those principals.
- Monitor internal Splunk audit logs for repeated calls to LDAP authentication configuration endpoints from the same session within short time windows.
- Alert on anomalous CPU consumption on Splunk search heads and indexers that coincides with authenticated administrative activity.
Monitoring Recommendations
- Forward _audit and _internal indexes to a centralized monitoring tier for retention and correlation across the deployment.
- Create dashboards tracking per-user API call rates to authentication management endpoints.
- Baseline normal LDAP configuration activity so bursts of bind requests surface as outliers.
How to Mitigate CVE-2025-20370
Immediate Actions Required
- Upgrade Splunk Enterprise to version 10.0.1, 9.4.4, 9.3.6, or 9.2.8 or later as applicable to the deployed branch.
- Confirm Splunk Cloud Platform tenants are running 9.3.2411.108, 9.3.2408.118, or 9.2.2406.123 or later; coordinate with Splunk support where needed.
- Review all roles that inherit the change_authentication capability and remove it from roles that do not require authentication scheme management.
Patch Information
Splunk released fixed builds documented in Splunk Security Advisory SVD-2025-1005. Splunk Cloud Platform customers receive the fix through the Splunk-managed update process. On-premises administrators should plan an upgrade window and validate authentication, search head clustering, and indexer cluster health after patching.
Workarounds
- Restrict the change_authentication capability to a minimal set of trusted administrators until patches are applied.
- Require multi-factor authentication for all accounts carrying high-privilege Splunk capabilities to raise the bar for session compromise.
- Monitor and rate-limit administrative API usage at an upstream reverse proxy where feasible, blocking repeated requests to LDAP configuration endpoints.
- Prepare a documented restart runbook so operators can recover service quickly if CPU exhaustion occurs.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
