CVE-2026-34046: Langflow: Authenticated Users Can Read, Modify, and Delete Any Flow via Missing Ownership Check

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-03-27 · updated 2026-10-26
Weakness: CWE-639

Description

Langflow is a tool for building and deploying AI-powered agents and workflows. Prior to version 1.5.1, the `_read_flow` helper in `src/backend/base/langflow/api/v1/flows.py` branched on the `AUTO_LOGIN` setting to decide whether to filter by `user_id`. When `AUTO_LOGIN` was `False` (i.e., authentication was enabled), neither branch enforced an ownership check — the query returned any flow matching the given UUID regardless of who owned it. This allowed any authenticated user to read any other user's flow, including embedded plaintext API keys; modify the logic of another user's AI agents, and/or delete flows belonging to other users. The vulnerability was introduced by the conditional logic that was meant to accommodate public/example flows (those with `user_id = NULL`) under auto-login mode, but inadvertently left the authenticated path without an ownership filter. The fix in version 1.5.1 removes the `AUTO_LOGIN` conditional entirely and unconditionally scopes the query to the requesting user.

Affected products

IBM Langflow OSS: before 1.5.0; 1.5.0-dev0, 1.5.0-dev1 — fixed in 1.5.0
langflow-ai langflow-base: before 0.5.1 — fixed in 0.5.1

How to fix

Upgrade to a fixed version: IBM Langflow OSS 1.5.0; langflow-ai langflow-base 0.5.1. Check the vendor advisory for mitigations.

References

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