CVE-2025-20229: Splunk Enterprise RCE Vulnerability

CVE-2025-20229 Overview

CVE-2025-20229 is a Remote Code Execution (RCE) vulnerability affecting Splunk Enterprise and Splunk Cloud Platform. The vulnerability allows a low-privileged user who does not hold the "admin" or "power" Splunk roles to execute arbitrary code by uploading malicious files to the $SPLUNK_HOME/var/run/splunk/apptemp directory. This security flaw stems from missing authorization checks in the file upload functionality.

Critical Impact

Low-privileged attackers can achieve Remote Code Execution on Splunk servers through unauthorized file uploads, potentially leading to complete system compromise and access to sensitive log data.

Affected Products

• Splunk Enterprise versions below 9.3.3, 9.2.5, and 9.1.8
• Splunk Enterprise version 9.4.0
• Splunk Cloud Platform versions below 9.3.2408.104, 9.2.2406.108, 9.2.2403.114, and 9.1.2312.208

Discovery Timeline

• 2025-03-26 - CVE-2025-20229 published to NVD
• 2025-07-21 - Last updated in NVD database

Technical Details for CVE-2025-20229

Vulnerability Analysis

This vulnerability is classified under CWE-284 (Improper Access Control), which occurs when a software component does not properly restrict access to resources or functionality. In the context of Splunk, the application fails to validate whether a user has sufficient privileges before allowing file uploads to a sensitive application temporary directory.

The attack requires network access and user interaction, but can be executed by any authenticated user with low-level privileges. Successful exploitation results in high impact to confidentiality, integrity, and availability of the affected system. Given Splunk's role as a centralized logging and security information platform, compromise could expose sensitive organizational data and potentially serve as a pivot point for further attacks.

Root Cause

The root cause is missing authorization checks in the file upload mechanism. When users attempt to upload files to the $SPLUNK_HOME/var/run/splunk/apptemp directory, the application does not verify whether the requesting user holds the required "admin" or "power" Splunk roles. This allows any authenticated user, regardless of their assigned privileges, to upload files to this directory.

Attack Vector

The attack is network-based and requires the attacker to have valid credentials for a low-privileged Splunk account. The attacker exploits the missing authorization checks by:

1. Authenticating to Splunk with any valid user account
2. Crafting a malicious file designed for code execution
3. Uploading the file to the $SPLUNK_HOME/var/run/splunk/apptemp directory
4. Triggering execution of the uploaded malicious content

The apptemp directory is used by Splunk for temporary application files, and content placed there may be processed or executed by the Splunk application engine. By uploading specially crafted files, an attacker can achieve arbitrary code execution within the context of the Splunk service.

Detection Methods for CVE-2025-20229

Indicators of Compromise

• Unusual file uploads to the $SPLUNK_HOME/var/run/splunk/apptemp directory by non-admin users
• Unexpected files or scripts appearing in the apptemp directory
• Process spawning from Splunk service that deviates from normal operational patterns
• Authentication events from low-privileged accounts followed by file upload activity

Detection Strategies

• Monitor file system activity in the $SPLUNK_HOME/var/run/splunk/apptemp directory for unauthorized modifications
• Implement Splunk audit logging to track file upload operations and correlate with user privilege levels
• Create alerts for any file uploads performed by users without "admin" or "power" roles
• Review Splunk internal logs for suspicious REST API calls related to file upload endpoints

Monitoring Recommendations

• Enable comprehensive audit logging for all Splunk user activities
• Configure file integrity monitoring (FIM) on the apptemp directory and other sensitive Splunk paths
• Establish baseline behavior for legitimate file upload patterns and alert on deviations
• Monitor for child processes spawned by the Splunk daemon that may indicate code execution

How to Mitigate CVE-2025-20229

Immediate Actions Required

• Upgrade Splunk Enterprise to versions 9.3.3, 9.2.5, or 9.1.8 (or later) immediately
• For Splunk Cloud Platform, upgrade to versions 9.3.2408.104, 9.2.2406.108, 9.2.2403.114, or 9.1.2312.208 (or later)
• Audit all user accounts to ensure principle of least privilege is enforced
• Review recent file upload activity for signs of exploitation

Patch Information

Splunk has released security patches addressing this vulnerability. Refer to the Splunk Security Advisory SVD-2025-0301 for detailed upgrade instructions and patch downloads.

For Splunk Enterprise, upgrade to:

• Version 9.3.3 or later for the 9.3.x branch
• Version 9.2.5 or later for the 9.2.x branch
• Version 9.1.8 or later for the 9.1.x branch

For Splunk Cloud Platform, upgrade to:

• Version 9.3.2408.104 or later for the 9.3.x branch
• Version 9.2.2406.108 or 9.2.2403.114 or later for the 9.2.x branch
• Version 9.1.2312.208 or later for the 9.1.x branch

Workarounds

• Restrict network access to Splunk management interfaces to trusted networks only
• Implement additional authentication controls such as multi-factor authentication for Splunk access
• Apply strict access control lists to limit which users can authenticate to Splunk
• Consider placing additional file system restrictions on the apptemp directory as a defense-in-depth measure
• Monitor and log all file upload activity pending patch deployment

# Example: Restrict access to apptemp directory (temporary mitigation)
# Note: This may impact normal Splunk operations - test before applying
chmod 750 $SPLUNK_HOME/var/run/splunk/apptemp
chown splunk:splunk $SPLUNK_HOME/var/run/splunk/apptemp