CVE-2026-20165: Splunk Information Disclosure Vulnerability

CVE-2026-20165 Overview

A sensitive information disclosure vulnerability exists in Splunk Enterprise and Splunk Cloud Platform due to improper access control in the MongoClient logging channel. This vulnerability allows low-privileged users who do not hold the "admin" or "power" Splunk roles to retrieve sensitive information by inspecting a job's search log. The issue stems from insufficient access controls on logging data, classified as CWE-532 (Insertion of Sensitive Information into Log File).

Critical Impact

Low-privileged Splunk users can access sensitive information through search job logs, potentially exposing credentials, internal configuration data, or other confidential information logged by the MongoClient component.

Affected Products

• Splunk Enterprise versions below 10.2.1, 10.0.4, 9.4.9, and 9.3.10
• Splunk Cloud Platform versions below 10.2.2510.7, 10.1.2507.17, 10.0.2503.12, and 9.3.2411.124

Discovery Timeline

• 2026-03-11 - CVE CVE-2026-20165 published to NVD
• 2026-03-12 - Last updated in NVD database

Technical Details for CVE-2026-20165

Vulnerability Analysis

This vulnerability is categorized as an Information Disclosure issue resulting from improper access control in the MongoClient logging channel within Splunk Enterprise and Splunk Cloud Platform. The flaw allows authenticated users with minimal privileges to access sensitive information that should be restricted to administrative roles.

The core issue lies in how Splunk handles access controls for search job logs. When MongoClient operations are logged, the logging mechanism fails to properly restrict access based on user roles. This means any authenticated user can inspect search job logs and potentially extract sensitive information such as connection strings, credentials, or internal system details that are inadvertently logged during MongoClient operations.

The attack requires network access and valid authentication credentials, but only minimal privileges are needed beyond basic authentication. The vulnerability affects confidentiality, integrity, and availability to a limited degree, as attackers could leverage exposed information for further attacks on the system.

Root Cause

The root cause of CVE-2026-20165 is improper access control (CWE-532) in the MongoClient logging channel. The logging mechanism does not adequately validate user permissions before exposing job search logs, allowing users without "admin" or "power" roles to access sensitive logged information. This represents a failure to implement the principle of least privilege for logging data access.

Attack Vector

The attack vector for this vulnerability is network-based and requires low-privileged authenticated access. An attacker would:

1. Authenticate to the Splunk instance with any valid user account
2. Navigate to or query search job logs
3. Inspect the MongoClient logging channel data within job search logs
4. Extract sensitive information such as connection details, credentials, or internal configuration data

The vulnerability exploits the gap between what information is logged and who is permitted to view those logs. Since no special interaction is required and the attack can be performed over the network, exploitation is relatively straightforward for any authenticated user.

Detection Methods for CVE-2026-20165

Indicators of Compromise

• Unusual access patterns to search job logs by non-administrative users
• Low-privileged user accounts querying or accessing MongoClient-related log entries
• Anomalous API calls to retrieve job search log data from accounts without admin or power roles

Detection Strategies

• Monitor Splunk audit logs for access to search job logs by users without admin or power roles
• Implement alerting for low-privileged accounts accessing logging channels typically reserved for administrative operations
• Review user activity reports for patterns of log inspection that exceed normal operational needs

Monitoring Recommendations

• Enable detailed auditing of search job log access within your Splunk deployment
• Configure SIEM rules to detect unauthorized log access attempts based on user role
• Regularly review access patterns to sensitive logging data and investigate anomalies

How to Mitigate CVE-2026-20165

Immediate Actions Required

• Upgrade Splunk Enterprise to version 10.2.1, 10.0.4, 9.4.9, or 9.3.10 or later depending on your release track
• Upgrade Splunk Cloud Platform to version 10.2.2510.7, 10.1.2507.17, 10.0.2503.12, or 9.3.2411.124 or later
• Review user accounts and ensure appropriate role assignments following the principle of least privilege
• Audit recent access to search job logs to identify potential prior exploitation

Patch Information

Splunk has released security updates addressing this vulnerability. Detailed patch information and upgrade instructions are available in the Splunk Security Advisory SVD-2026-0304. Organizations should prioritize upgrading to the fixed versions for their respective deployment type (Enterprise or Cloud Platform).

Workarounds

• Restrict network access to Splunk instances to trusted users and networks while awaiting patch deployment
• Review and tighten role-based access controls for users who do not require access to search job logs
• Consider temporarily disabling or restricting access to the MongoClient logging channel if operationally feasible
• Monitor for suspicious log access activity as an interim detective control