CVE-2026-49257 Microsoft Sentinel · KQL

Detect CVE-2026-49257: mcp-pinot Unauthenticated Tool Invocation via Default oauth_enabled=False in Microsoft Sentinel

Detects exploitation of CVE-2026-49257, a critical authentication bypass in mcp-pinot-server (<=3.0.1). The server defaults to oauth_enabled=False and binds to 0.0.0.0, allowing any network-adjacent or internet-facing attacker to invoke MCP tools without authentication. CVSS 10.0 with public PoC available.

MITRE ATT&CK

Tactic
Initial Access Privilege Escalation Exfiltration

KQL Detection Query

Microsoft Sentinel (KQL)
kusto 
union DeviceNetworkEvents, CommonSecurityLog
| where TimeGenerated > ago(24h)
| where DestinationPort in (8000, 8080, 8443, 9000, 3000)
| where (ProcessCommandLine has "mcp-pinot" or ProcessCommandLine has "mcp_pinot" or ProcessCommandLine has "uvicorn" or ProcessCommandLine has "fastapi")
| where not (InitiatingProcessAccountName in ("serviceaccount", "mcp-service"))
| extend AuthHeader = extract("Authorization: (\\S+)", 1, AdditionalExtensions)
| where isempty(AuthHeader) or AuthHeader == ""
| project TimeGenerated, DeviceName, RemoteIP, DestinationPort, ProcessCommandLine, InitiatingProcessAccountName, AuthHeader
| order by TimeGenerated desc
critical severity medium confidence

Detects inbound HTTP connections to mcp-pinot-server processes on common MCP ports without an Authorization header, indicating unauthenticated tool invocation attempts consistent with CVE-2026-49257 exploitation.

Data Sources

DeviceNetworkEventsCommonSecurityLogAzureActivity

Required Tables

DeviceNetworkEventsCommonSecurityLog

False Positives & Tuning

  • Internal service-to-service calls on trusted networks where authentication is handled at the network layer
  • Health check endpoints or monitoring probes that do not send auth headers
  • Development or staging environments where oauth_enabled is intentionally False
  • Load balancer health checks hitting the MCP server directly

Other platforms for CVE-2026-49257

Splunk (SPL) Elastic Security (Elastic) IBM QRadar (QRadar) Sumo Logic CSE (Sumo) Google Chronicle (YARA-L) CrowdStrike LogScale (LogScale) All platforms (combined) →

Testing Methodology

Validate this detection against 4 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.

  1. Test 1Verify Unauthenticated MCP Tool Listing

    Expected signal: HTTP 200 response with JSON list of available Pinot MCP tools returned without any authentication challenge; no 401 or 403 status code issued.

  2. Test 2Unauthenticated Pinot Query Execution via MCP Tool

    Expected signal: Pinot query execution log entry showing query 'SELECT * FROM myTable LIMIT 10' from MCP server without session token; HTTP 200 from mcp-pinot-server with query results in response body.

  3. Test 3External Network Exploitation Simulation

    Expected signal: Inbound TCP connection from external IP to port 8000; HTTP POST to /tools/list and /tools/call with source IP from outside trusted ranges; no TLS client certificate or Authorization header present.

  4. Test 4Confirm Vulnerable Package Version in Environment

    Expected signal: Command execution events showing pip, find, and ps commands with mcp-pinot arguments; output revealing package version <= 3.0.1 and running process details.

Last updated: 2026-06-27 Research depth: standard
References (6)

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