CVE-2026-6542: Monitor API allows cross-user read of transaction logs and deletion of build data via flow_id

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

• langflow langflow1.0.0 and later · before 1.9.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (ibm). Independent of NVD's CPE analysis and usually ahead of it.

• IBM Langflow OSS

  • 1.0.0 and later · up to and including 1.8.4affected · semver

Other highest-scoring records for the same primary product.

• CVE-2025-3248Langflow < 1.3.0 Unauthenticated RCE via /api/v1/validate/codeKEV
  99Now
• CVE-2026-33017Langflow has Unauthenticated Remote Code Execution via Public Flow Build EndpointKEV
  96Now
• CVE-2025-34291Langflow <= 1.6.9 CORS Misconfiguration to Token Hijack & RCEKEV
  95Now

Published before and after this one in the same product

• ← EarlierCVE-2026-34046Mar 27, 2026 · Langflow: Authenticated Users Can Read, Modify, and Delete Any Flow via Missing Ownership Check
  34Monitor
• ← EarlierCVE-2026-3357Apr 7, 2026 · IBM Langflow Desktop FAISS Vector Store Remote Code Execution via malicious Pickle file
  35Monitor
• Later →CVE-2026-42048May 12, 2026 · Langflow: Path Traversal in Langflow Knowledge Bases API
  39Monitor

Root cause

The endpoint fetches the record by the ID sent in the request, but never checks whether the record belongs to the requesting user.

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

1const invoice = await Invoice.findById(req.params.id);2res.json(invoice);

1const invoice = await Invoice.findOne({2  id: req.params.id,3  ownerId: req.user.id,4});5if (!invoice) return res.sendStatus(404);6res.json(invoice);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.