CVE-2025-20228: Splunk Enterprise CSRF Vulnerability

CVE-2025-20228 Overview

CVE-2025-20228 is a Cross-Site Request Forgery (CSRF) vulnerability affecting Splunk Enterprise and Splunk Cloud Platform. The flaw allows a low-privileged user, who does not hold the admin or power Splunk roles, to change the maintenance mode state of the App Key Value Store (KVStore). Exploitation requires the victim to interact with an attacker-controlled resource, such as a crafted web page or link. The vulnerability is tracked under CWE-352 and impacts the availability of the KVStore service.

Critical Impact
A successful CSRF attack can toggle KVStore maintenance mode, disrupting availability of applications and features that rely on KVStore data.

Affected Products

Splunk Enterprise versions below 9.3.3, 9.2.5, and 9.1.8
Splunk Cloud Platform versions below 9.2.2403.108
Splunk Cloud Platform versions below 9.1.2312.204

Discovery Timeline

2025-03-26 - CVE-2025-20228 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-20228

Vulnerability Analysis

The vulnerability resides in the Splunk web interface handling of KVStore maintenance mode state changes. The endpoint responsible for toggling maintenance mode does not adequately validate the origin of state-changing requests. An authenticated low-privileged user, lacking admin or power roles, becomes the vector when they visit an attacker-controlled page while logged into Splunk. The attacker-controlled page issues a forged request that Splunk processes using the victim's session credentials.

The KVStore is a critical component that stores application state, lookup data, and configuration for many Splunk apps. Placing the KVStore into maintenance mode makes it read-only and can interrupt dependent app functionality, dashboards, and scheduled searches.

Root Cause

The root cause is missing or insufficient CSRF protection on the KVStore maintenance mode endpoint. The server accepts state-changing requests without verifying anti-CSRF tokens or enforcing strict origin checks against the request's Origin or Referer headers.

Attack Vector

Exploitation occurs over the network and requires user interaction. An attacker crafts a malicious web page containing an automatically submitted form or fetch request targeting the Splunk KVStore maintenance mode endpoint. When a low-privileged authenticated Splunk user loads the page in a browser holding an active Splunk session, the browser transmits session cookies alongside the forged request. Splunk processes the request under the victim's identity, altering the KVStore maintenance state.

Refer to the Splunk Security Advisory SVD-2025-0303 for vendor-supplied technical details.

Detection Methods for CVE-2025-20228

Indicators of Compromise

Unexpected transitions of KVStore into or out of maintenance mode without a corresponding administrator action
Splunk web access logs showing state-change POST requests to KVStore endpoints originating from low-privileged user sessions
HTTP requests to Splunk web with Referer or Origin headers pointing to external, untrusted domains

Detection Strategies

Audit Splunk internal logs (_internal index) for KVStore maintenance mode toggle events and correlate against the acting user's role
Alert on any KVStore state change performed by accounts without admin or power roles
Inspect web access logs for cross-origin requests targeting Splunk management endpoints

Monitoring Recommendations

Ingest Splunk web access and audit logs into a centralized SIEM for correlation and long-term retention
Monitor for anomalous session activity, including requests initiated shortly after external navigation events
Track KVStore availability metrics to identify unexpected outages that may indicate exploitation

How to Mitigate CVE-2025-20228

Immediate Actions Required

Upgrade Splunk Enterprise to version 9.3.3, 9.2.5, 9.1.8, or later
Upgrade Splunk Cloud Platform to version 9.2.2403.108, 9.1.2312.204, or later
Review Splunk role assignments and remove unnecessary user accounts that no longer require access
Enforce browser session hygiene, instructing users to log out of Splunk when not actively working

Patch Information

Splunk has released fixed versions addressing this CSRF flaw. Details are published in the Splunk Security Advisory SVD-2025-0303. Administrators should apply the corresponding fixed release for their deployment channel.

Workarounds

If immediate patching is not possible, restrict network access to the Splunk web interface using firewall rules or reverse proxy allowlists
Require users to access Splunk from dedicated browser profiles that do not visit untrusted sites
Enable and enforce Splunk's built-in CSRF protection settings in web.conf where available

bash

# Example web.conf hardening in $SPLUNK_HOME/etc/system/local/web.conf
[settings]
enableCSRFProtection = true
x_frame_options_sameorigin = true