# Security Vulnerability Analysis: SVD-2025-1210

## Executive Summary

**Date**: December 5, 2025
**Severity**: MEDIUM (CVSS 5.4)
**Status**: ✅ **ADDRESSED** - Different architecture than affected Splunk MCP Server

## Splunk Advisory Details

- **Advisory ID**: SVD-2025-1210
- **CVE ID**: CVE-2025-20381
- **Published**: December 3, 2025
- **CVSS v3.1 Score**: 5.4 (Medium)
- **CVSS Vector**: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
- **CWE**: CWE-863 (Incorrect Authorization)

### Vulnerability Description

In Splunk MCP Server app versions below 0.2.4, a user with access to the "run_splunk_query" MCP tool could bypass SPL command allowlist controls by embedding SPL commands as sub-searches (using square brackets `[]`), leading to unauthorized actions beyond the intended MCP restrictions.

## Our Architecture - Key Difference

**This project (deslicer/mcp-for-splunk) uses a fundamentally different security model than the affected Splunk MCP Server app.**

### Splunk MCP Server (Affected)
- Implements its own SPL command allowlist
- Subsearches bypass the allowlist → **VULNERABLE**

### Our Implementation (deslicer/mcp-for-splunk)
- **Does NOT implement command allowlists** that can be bypassed
- **Relies on Splunk RBAC** for all authorization
- Users authenticate with their own Splunk credentials
- Splunk Enterprise enforces index access and command permissions
- **Subsearches execute with the authenticated user's permissions** → No bypass possible

## Security Model

### How We Handle Authorization

1. **User Authentication**: Each MCP request uses the user's Splunk credentials
2. **Splunk RBAC**: Splunk Enterprise validates all queries against user's roles
3. **Index Access**: Controlled by Splunk roles, not MCP layer
4. **Command Permissions**: Controlled by Splunk capabilities, not MCP layer

### Why CVE-2025-20381 Doesn't Apply

The vulnerability exists when:
1. MCP layer has an allowlist that restricts commands
2. Subsearches bypass that MCP-layer allowlist
3. Splunk executes commands the MCP intended to block

In our architecture:
1. We don't have an MCP-layer allowlist to bypass
2. All authorization is delegated to Splunk RBAC
3. Subsearches run with the same permissions as the parent query

## What We DO Protect Against

Our `src/core/security.py` module blocks:

| Command | Reason |
|---------|--------|
| `collect` | Data exfiltration to new indexes |
| `outputlookup` | Writing data to lookups |
| `outputcsv` | Writing data to CSV files |
| `delete` | Data deletion |
| `sendemail` | External communication |
| `script` | External script execution |
| `run` | External command execution |

These are blocked at the MCP layer as **defense in depth** - they represent data modification or external execution that should require explicit user action, not automated agent execution.

### Complexity Limits

- **Max query length**: 50,000 characters (prevent DoS)
- **Max pipeline depth**: 50 pipes (prevent resource exhaustion)

## Recommendations for Operators

1. **Use dedicated Splunk accounts** for MCP access with appropriate role restrictions
2. **Configure Splunk roles** to limit index access based on user needs
3. **Enable Splunk audit logging** to monitor MCP-initiated searches
4. **Review Splunk capabilities** assigned to MCP user roles

## Security Scanning

This PR adds comprehensive security scanning:

- **Bandit**: Python SAST scanning
- **Semgrep**: Multi-language SAST with security rules
- **Trivy**: Dependency vulnerability scanning
- **Gitleaks**: Secret detection
- **CodeQL**: Advanced security analysis

## References

- [Splunk Advisory SVD-2025-1210](https://advisory.splunk.com/advisories/SVD-2025-1210)
- [CVE-2025-20381](https://nvd.nist.gov/vuln/detail/CVE-2025-20381)
- [Splunk RBAC Documentation](https://docs.splunk.com/Documentation/Splunk/latest/Security/Aboutusersandroles)

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**Last Updated**: December 8, 2025
**Status**: ✅ ANALYZED - Not affected due to architectural differences
