Langflow: IDOR/BOLA in Monitor API — Missing Ownership Enforcement on 7 Endpoints

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

8.8 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS

• CVE-2026-33760: 0.50% estimated exploitation activity in the next 30 days; percentile 42.53 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary Langflow's /api/v1/monitor router exposes 7 endpoints that perform read, write, and delete operations on user-owned resources — messages, sessions, build artifacts, and LLM transaction logs — without verifying that the authenticated requester owns the targeted resource. Any authenticated user can read, modify, rename, or permanently delete another user's data by supplying the target's resource ID or flowid. This is a classic IDOR/BOLA vulnerability. Notably, the same source file (monitor.py) contains one correctly-implemented endpoint that uses an ownership check, demonstrating the correct pattern was known but inconsistently applied. Details Source file: src/backend/base/langflow/api/v1/monitor.py The correct pattern (used only in GET /monitor/messages, lines 77–80): All 7 vulnerable endpoints are missing this guard: 1. GET /api/v1/monitor/builds (lines 27–33) — reads build data for any flowid: 2. DELETE /api/v1/monitor/messages (lines 102–107) — deletes any message by UUID:…

Published by the source

16 Jun 2026, 17:34 UTC

Last modified by the source

20 Jul 2026, 13:45 UTC

Source last checked

26 Oct 2026, 13:49 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-9c59-2mvc-vfr8

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-9c59-2mvc-vfr8

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# Patch Next advisory brief: CVE-2026-33760

Advisory: Langflow: IDOR/BOLA in Monitor API — Missing Ownership Enforcement on 7 Endpoints
IDs: CVE-2026-33760, GHSA-9c59-2mvc-vfr8
Record: https://patchnext.com/advisories/cve-2026-33760 (revision 2, source checked 26 Oct 2026, 13:49 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: langflow 1.9.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI langflow: affected < 1.9.0; fixed in 1.9.0

## Suggested inspection (read-only)
- `python -m pip show langflow`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on langflow.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-9c59-2mvc-vfr8 (OSV record GHSA-9c59-2mvc-vfr8 lists affected ranges: PyPI langflow >=0 <1.9.0 (fixed))
- Verified: https://github.com/advisories/GHSA-9c59-2mvc-vfr8 (GitHub-reviewed advisory GHSA-9c59-2mvc-vfr8 lists affected ranges: PyPI langflow >=0 <1.9.0)

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