CVE-2026-76398: Splunk AI Toolkit Auth Bypass Vulnerability

CVE-2026-76398 Overview

CVE-2026-76398 is a missing authorization vulnerability [CWE-862] in Splunk AI Toolkit versions below 6.0.1. A low-privileged user who does not hold the admin or power Splunk roles can delete another user's experiment history through the Representational State Transfer (REST) API. The flaw exists because Splunk AI Toolkit deletes experiment history before verifying that the requesting user has permission to delete the associated experiment. The issue affects the integrity of experiment data stored within the toolkit.

Critical Impact
An authenticated low-privileged user can delete experiment history belonging to other users through the REST API, causing loss of machine learning experiment data.

Affected Products

Splunk AI Toolkit versions below 6.0.1
Splunk Cloud Platform deployments running vulnerable Splunk AI Toolkit versions
Splunk Enterprise deployments with vulnerable Splunk AI Toolkit installed

Discovery Timeline

2026-08-19 - CVE-2026-76398 published to NVD
2026-08-20 - Last updated in NVD database

Technical Details for CVE-2026-76398

Vulnerability Analysis

The vulnerability resides in the experiment deletion workflow of the Splunk AI Toolkit. When a user issues a delete request through the REST API, the toolkit removes the experiment history records before performing the authorization check against the associated experiment. This ordering error creates a window where a low-privileged authenticated user can trigger deletion of another user's experiment history without possessing the admin or power role.

The issue is classified as Missing Authorization [CWE-862]. The vulnerability affects data integrity only. Confidentiality and availability of the Splunk platform itself remain unaffected, though the loss of experiment history can disrupt machine learning workflows.

Exploitation requires network access to the Splunk REST API and valid low-privileged credentials. No user interaction is needed to trigger the deletion once a crafted API request is submitted.

Root Cause

The root cause is an out-of-order authorization check. The application performs the destructive action (DELETE on experiment history) prior to validating whether the caller owns or has rights to manage the parent experiment object. Splunk's role-based access controls that normally restrict such operations to the admin or power roles are not consulted before the write occurs.

Attack Vector

An attacker authenticates to the target Splunk instance using any account without elevated privileges. The attacker then sends a REST API request against the experiment history endpoint of the Splunk AI Toolkit, referencing an experiment owned by another user. The toolkit processes the deletion before evaluating ownership, and the target user's experiment history is removed.

For endpoint and API details, see the Splunk Security Advisory SVD-2026-0808.

Detection Methods for CVE-2026-76398

Indicators of Compromise

Unexpected DELETE requests to Splunk AI Toolkit experiment history REST endpoints from accounts lacking the admin or power role.
Missing or truncated experiment history for users who did not initiate deletions.
Audit log entries showing experiment history removal followed by failed authorization events for the same object.

Detection Strategies

Enable and review Splunk _audit index entries for REST API calls targeting AI Toolkit experiment endpoints.
Correlate deletion actions with the initiating user's role assignments to flag operations performed by non-privileged accounts.
Alert on cross-user access patterns where one user's session deletes objects owned by another user.

Monitoring Recommendations

Baseline normal experiment lifecycle activity per user, then alert on deviations such as bulk deletions or off-hours activity.
Monitor REST API traffic to /servicesNS/ paths associated with the AI Toolkit for anomalous DELETE verbs.
Retain audit logs for a sufficient period to reconstruct experiment history changes if abuse is suspected.

How to Mitigate CVE-2026-76398

Immediate Actions Required

Upgrade Splunk AI Toolkit to version 6.0.1 or later on all Splunk Enterprise and Splunk Cloud Platform deployments.
Review recent audit logs for unauthorized deletions of experiment history and restore from backup where possible.
Audit accounts with access to the Splunk AI Toolkit and remove unnecessary user access to reduce the exploitation surface.

Patch Information

Splunk has addressed the vulnerability in Splunk AI Toolkit version 6.0.1. Refer to the Splunk Security Advisory SVD-2026-0808 for official patch details and upgrade instructions. Consult the Experiment Assistants documentation for context on affected functionality.

Workarounds

Restrict access to the Splunk AI Toolkit application to trusted users only until the patch is applied.
Limit REST API access on the Splunk management port (default 8089) to trusted networks using firewall rules.
Increase audit logging verbosity for AI Toolkit endpoints to accelerate detection of abuse attempts.

bash

# Verify installed Splunk AI Toolkit version
$SPLUNK_HOME/bin/splunk display app Splunk_ML_Toolkit

# Upgrade the app via the CLI after downloading the fixed package
$SPLUNK_HOME/bin/splunk install app <path-to-splunk-ai-toolkit-6.0.1>.tgz -update 1 -auth <admin>:<password>

# Restart Splunk to apply the update
$SPLUNK_HOME/bin/splunk restart