Detect Langflow IDOR: Unauthorized Access to Another User's Flow via /api/v1/responses in IBM QRadar
CVE-2026-55255 is a critical IDOR (Insecure Direct Object Reference) vulnerability in Langflow versions prior to 1.9.1. An authenticated attacker can enumerate and access another user's flow data by manipulating object identifiers in requests to the /api/v1/responses endpoint. With a CVSS score of 9.9, this vulnerability allows horizontal privilege escalation between users, potentially exposing sensitive AI flow configurations, credentials embedded in flows, and proprietary automation logic.
MITRE ATT&CK
- Tactic
- Credential Access Collection
QRadar Detection Query
SELECT
sourceip,
"HTTP User-Agent" AS user_agent,
COUNT(*) AS request_count,
COUNT(DISTINCT REGEXP_EXTRACT(URL, '/api/v1/responses/([^/?]+)', 1)) AS distinct_flow_ids,
MIN(starttime) AS first_seen,
MAX(starttime) AS last_seen
FROM events
WHERE
LOGSOURCETYPENAME(devicetype) IN ('Apache HTTP Server', 'Nginx', 'F5 BIG-IP LTM')
AND URL ILIKE '%/api/v1/responses/%'
AND responseCode = 200
AND starttime >= (DATEADD('hour', -24, now()))
GROUP BY
sourceip,
"HTTP User-Agent",
DATEADD('minute', -(MOD(MINUTE(starttime), 10)), starttime)
HAVING
COUNT(DISTINCT REGEXP_EXTRACT(URL, '/api/v1/responses/([^/?]+)', 1)) >= 5
ORDER BY distinct_flow_ids DESCQRadar AQL query detecting Langflow IDOR enumeration by aggregating successful requests to the /api/v1/responses endpoint, flagging source IPs that access five or more distinct flow IDs within a 10-minute window.
Data Sources
Required Tables
False Positives & Tuning
- Langflow platform administrators performing cross-user flow audits with legitimate access
- Automated integration systems consuming results from many flows owned by the same account
- Pentest or red team activity against authorised Langflow environments
- Langflow batch export features that internally enumerate flow IDs
Other platforms for CVE-2026-55255
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 Flow ID Discovery via /api/v1/responses
Expected signal: 20 GET requests to /api/v1/responses/* within seconds, all from the same source IP and Authorization header, appearing in web/application access logs
- Test 2Targeted Cross-User Flow Access Using Known Flow ID
Expected signal: Single authenticated GET request to /api/v1/responses/<victim_flow_id> returning HTTP 200 with flow response data belonging to a different user
- Test 3Scripted Flow Enumeration with Response Exfiltration
Expected signal: 50 GET requests to /api/v1/responses/* within approximately 30 seconds, with a subset returning HTTP 200 and response bodies containing flow data; all from single source IP
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