CVE-2026-20144: Splunk Enterprise Information Disclosure

CVE-2026-20144 Overview

CVE-2026-20144 is an Information Disclosure vulnerability affecting Splunk Enterprise and Splunk Cloud Platform deployments utilizing Search Head Cluster (SHC) configurations. The vulnerability allows users with access to the _internal index to view Security Assertion Markup Language (SAML) configurations for Attribute Query Requests (AQRs) or Authentication extensions in plain text within the conf.log file.

This vulnerability is classified under CWE-532 (Insertion of Sensitive Information into Log File), where sensitive SAML configuration data is inadvertently written to log files accessible by privileged users.

Critical Impact

Exposure of SAML authentication configurations could allow attackers with internal access to compromise authentication mechanisms, potentially leading to unauthorized access or identity spoofing within affected Splunk deployments.

Affected Products

• Splunk Enterprise versions below 10.2.0, 10.0.2, 9.4.7, 9.3.8, and 9.2.11
• Splunk Cloud Platform versions below 10.2.2510.0, 10.1.2507.11, 10.0.2503.9, and 9.3.2411.120
• Splunk Search Head Cluster (SHC) deployments with SAML AQR or Authentication extensions configured

Discovery Timeline

• 2026-02-18 - CVE-2026-20144 published to NVD
• 2026-02-19 - Last updated in NVD database

Technical Details for CVE-2026-20144

Vulnerability Analysis

This vulnerability exists in Splunk's logging mechanism for Search Head Cluster deployments. When SAML-based authentication is configured with either Attribute Query Requests (AQRs) or Authentication extensions, the system inadvertently logs sensitive configuration details to the conf.log file in plain text format.

The exposure requires that an attacker holds a role with access to the Splunk _internal index, which contains internal logs and metrics. While this limits the attack surface to authenticated users with elevated privileges, it violates the principle of least privilege by exposing authentication configuration data that should remain protected even from users with internal index access.

The vulnerability stems from improper handling of sensitive data during the logging process. SAML configurations may contain critical authentication parameters, including identity provider details, assertion handling configurations, and potentially cryptographic material used in the authentication flow.

Root Cause

The root cause is CWE-532 (Insertion of Sensitive Information into Log File). The Splunk logging subsystem fails to properly sanitize or redact SAML configuration data before writing to the conf.log file. This results in sensitive authentication configuration being persisted in plain text format, accessible to any user with _internal index read permissions.

Attack Vector

The attack requires adjacent network access and high privileges, as indicated by the CVSS vector. An attacker would need:

1. Valid authentication to the Splunk deployment
2. A role with read access to the _internal index
3. Access to a Search Head Cluster environment with SAML AQR or Authentication extensions configured

Once these conditions are met, the attacker can search the conf.log file within the _internal index to extract SAML configuration data. This information could then be used to understand the authentication architecture, identify potential weaknesses, or facilitate further attacks against the SAML infrastructure.

For technical details on the vulnerability mechanism, refer to the Splunk Security Advisory SVD-2026-0209.

Detection Methods for CVE-2026-20144

Indicators of Compromise

• Unusual search activity targeting the _internal index, specifically queries referencing conf.log or SAML-related terms
• Access to conf.log files by users who do not typically require access to internal logging data
• Audit log entries showing repeated or extensive access to the _internal index by non-administrative users

Detection Strategies

• Implement Splunk audit logging to track all searches against the _internal index and configure alerts for suspicious query patterns
• Create correlation searches to identify users accessing SAML-related log entries who do not have a legitimate operational need
• Monitor for bulk export or download activities targeting internal log files

Monitoring Recommendations

• Enable and review Splunk's built-in audit trail for search activities on sensitive indexes
• Configure real-time alerts for any search queries containing SAML, AQR, or authentication configuration keywords against conf.log
• Regularly review role assignments to ensure only necessary personnel have access to the _internal index

How to Mitigate CVE-2026-20144

Immediate Actions Required

• Upgrade Splunk Enterprise to versions 10.2.0, 10.0.2, 9.4.7, 9.3.8, or 9.2.11 or later depending on your version branch
• Upgrade Splunk Cloud Platform to versions 10.2.2510.0, 10.1.2507.11, 10.0.2503.9, or 9.3.2411.120 or later
• Review and audit all roles with access to the _internal index and restrict access to essential personnel only
• Examine existing conf.log files for sensitive SAML configuration data and consider log rotation or secure deletion of affected entries

Patch Information

Splunk has released security updates addressing this vulnerability. Organizations should apply the appropriate patch based on their current version branch. Detailed patch information and upgrade instructions are available in the Splunk Security Advisory SVD-2026-0209.

Workarounds

• Restrict access to the _internal index by modifying role capabilities to limit exposure until patches can be applied
• Implement additional access controls and monitoring on Search Head Cluster nodes to detect unauthorized log access
• Consider temporarily disabling SAML AQR or Authentication extensions if they are not critical to operations while awaiting patch deployment

# Example: Restricting _internal index access in authorize.conf
# Add to $SPLUNK_HOME/etc/system/local/authorize.conf

[role_restricted_user]
srchIndexesAllowed = main;summary
# Remove _internal from allowed indexes for non-administrative roles