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Upgrade to ProDetect MCP Memory Service Unauthenticated Document API Access (CVE-2026-50027) in Microsoft Sentinel
Detects exploitation of CVE-2026-50027, a missing authentication vulnerability (CWE-306) in mcp-memory-service versions prior to 10.67.1 that allows unauthenticated attackers to read, write, and delete stored memory documents via exposed API endpoints. Successful exploitation grants full unauthenticated access to sensitive memory/document contents, enabling data exfiltration, tampering, or destruction of stored AI agent memory state.
MITRE ATT&CK
- Tactic
- Initial Access Collection Impact
KQL Detection Query
let TargetPaths = dynamic(["/api/documents", "/api/memory", "/mcp/documents", "/documents"]);
CommonSecurityLog
| union (W3CIISLog)
| union (AzureDiagnostics | where Category == "ApplicationGatewayAccessLog")
| extend RequestUrl = coalesce(RequestURL, requestUri_s, cs_uri_stem_s)
| where RequestUrl has_any (TargetPaths)
| where HTTPMethod in ("GET", "POST", "PUT", "DELETE") or csMethod_s in ("GET", "POST", "PUT", "DELETE")
| where isempty(Authorization) or Authorization == "-" or isempty(User) or User == "-"
| summarize RequestCount = count(), Methods = make_set(HTTPMethod), Paths = make_set(RequestUrl) by SourceIP = coalesce(SourceIP, cIP_s), bin(TimeGenerated, 5m)
| where RequestCount > 5
| project TimeGenerated, SourceIP, RequestCount, Methods, PathsDetects unauthenticated HTTP requests to mcp-memory-service document/memory API endpoints from reverse proxy or web server logs ingested into Sentinel, flagging bursts of unauthenticated read/write/delete activity.
Data Sources
Required Tables
False Positives & Tuning
- Internal health check or monitoring probes hitting the same endpoints without auth headers
- Load balancer or reverse proxy logs that strip Authorization headers before logging
- Legitimate service-to-service calls using an authentication mechanism not captured in the logged fields
Other platforms for CVE-2026-50027
Testing Methodology
Validate this detection against 3 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.
- Test 1Unauthenticated GET to document API
Expected signal: HTTP GET request to /api/documents recorded in web/proxy access logs with no Authorization header present.
- Test 2Unauthenticated write to memory endpoint
Expected signal: HTTP POST request to /api/memory recorded in application logs with the injected content and no Authorization header.
- Test 3Unauthenticated delete of stored document
Expected signal: HTTP DELETE request to /api/documents/<id> recorded in access and application logs with no Authorization header, followed by removal of the document from the data store.
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