CVE-2026-76256: Splunk Information Disclosure Vulnerability

CVE-2026-76256 Overview

CVE-2026-76256 is an information disclosure vulnerability in Splunk Enterprise and Splunk Secure Gateway. Low-privileged authenticated users who do not hold the admin or power Splunk roles can read sensitive Security Assertion Markup Language (SAML) setup and instance settings configuration. The exposure occurs through Splunk Secure Gateway Representational State Transfer (REST) API endpoints that fail to enforce authorization checks before returning configuration data. The flaw is categorized under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor.

Critical Impact
Authenticated non-privileged users can retrieve SAML configuration and instance settings, exposing identity provider details that assist follow-on attacks against federated authentication.

Affected Products

Splunk Enterprise versions below 10.4.2, 10.2.6, 10.0.9, and 9.4.14
Splunk Secure Gateway versions below 3.10.9, 3.9.23, and 3.8.70
Deployments exposing Splunk Secure Gateway REST API endpoints to authenticated users

Discovery Timeline

2026-08-19 - CVE-2026-76256 published to the National Vulnerability Database
2026-08-20 - Last updated in NVD database

Technical Details for CVE-2026-76256

Vulnerability Analysis

The vulnerability resides in the Splunk Secure Gateway (SSG) application, which is bundled with Splunk Enterprise. SSG exposes REST API endpoints that return SAML setup and instance settings information. These endpoints omit the role-based authorization checks required to gate sensitive configuration data. Any authenticated Splunk user with a role below power or admin can query the endpoints and receive configuration content intended for administrators. The disclosed content may include identity provider metadata, entity identifiers, endpoint URLs, and instance-level settings useful for reconnaissance against federated authentication flows.

Root Cause

The root cause is a missing authorization control on the SAML-related SSG REST API endpoints. The endpoints authenticate the caller but do not verify that the caller holds a role authorized to read SAML configuration. This maps to CWE-200 and is a broken access control pattern in which authentication is treated as sufficient authorization.

Attack Vector

Exploitation requires network access to the Splunk management interface and valid credentials for any low-privileged Splunk role. An attacker sends authenticated HTTP requests to the vulnerable Splunk Secure Gateway REST endpoints and parses the returned configuration payloads. No user interaction is required, and confidentiality is the only impacted property. Refer to the Splunk Security Advisory SVD-2026-0801 for endpoint-specific technical details.

Detection Methods for CVE-2026-76256

Indicators of Compromise

Splunk audit log entries showing non-admin, non-power users issuing GET requests against Splunk Secure Gateway SAML and instance settings REST endpoints
Repeated REST API calls from a single low-privileged user account against multiple Secure Gateway configuration endpoints
Unexpected access patterns from service accounts or dashboard users toward administrative REST paths

Detection Strategies

Review _audit index events for REST API access to Splunk Secure Gateway endpoints correlated with the requesting user's role assignments
Alert on any successful HTTP 200 responses to Secure Gateway SAML configuration endpoints where the requestor is not in the admin or power role
Compare Splunk and Splunk Secure Gateway build versions against the patched releases listed in SVD-2026-0801

Monitoring Recommendations

Ingest Splunk internal audit and REST access logs into a centralized analytics platform for role-versus-endpoint correlation
Baseline normal Secure Gateway REST API usage per user and role, then alert on deviations
Monitor Splunk role assignments and capability grants for drift from least-privilege policy

How to Mitigate CVE-2026-76256

Immediate Actions Required

Upgrade Splunk Enterprise to version 10.4.2, 10.2.6, 10.0.9, or 9.4.14 or later, matching the appropriate release train
Upgrade Splunk Secure Gateway to 3.10.9, 3.9.23, or 3.8.70 or later
Audit existing Splunk user roles and remove unnecessary accounts or capabilities that could be leveraged for authenticated access

Patch Information

Splunk has released fixed builds referenced in Splunk Security Advisory SVD-2026-0801. The advisory lists the corrected Splunk Enterprise and Splunk Secure Gateway versions that enforce authorization checks on the affected SAML setup and instance settings REST API endpoints. Administrators running clustered deployments should apply upgrades across search heads, indexers, and any instance where Splunk Secure Gateway is installed.

Workarounds

Disable or uninstall the Splunk Secure Gateway application on instances where mobile and cloud gateway functionality is not required
Restrict network access to the Splunk management port so that only administrative users can reach REST endpoints
Enforce least-privilege role assignments and audit shared or low-privileged accounts that authenticate to Splunk

bash

# Verify the installed Splunk Secure Gateway version
$SPLUNK_HOME/bin/splunk display app splunk_secure_gateway

# Disable the app as a temporary workaround where upgrade is not immediately possible
$SPLUNK_HOME/bin/splunk disable app splunk_secure_gateway -auth admin:<password>
$SPLUNK_HOME/bin/splunk restart