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PatchSiren cyber security CVE debrief

CVE-2026-34046 Langflow CVE debrief

CVE-2026-34046 is a high-severity access-control vulnerability in Langflow. Before version 1.5.1, the `_read_flow` helper could return a flow by UUID without enforcing ownership when authentication was enabled, allowing an authenticated user to access other users' flows. The reported impact includes reading embedded plaintext API keys, modifying another user's AI agents, and deleting other users' flows. The fix in 1.5.1 removes the `AUTO_LOGIN` branch and always scopes the lookup to the requesting user.

Vendor
Langflow
Product
CVE-2026-34046
CVSS
HIGH 8.7
CISA KEV
Not listed in stored evidence
Original CVE published
2026-03-27
Original CVE updated
2026-05-11
Advisory published
2026-03-27
Advisory updated
2026-05-11

Who should care

Langflow administrators and operators, especially in multi-user or internet-facing deployments; developers who store secrets inside flows; and security teams responsible for access control, secret handling, and upgrade planning. Systems running Langflow versions prior to 1.5.1 should treat this as urgent.

Technical summary

The flaw is a server-side object authorization failure in `src/backend/base/langflow/api/v1/flows.py`. The `_read_flow` helper branched on `AUTO_LOGIN` to decide whether to filter by `user_id`, but when authentication was enabled neither branch enforced ownership, so a valid flow UUID could be fetched regardless of who owned it. NVD maps the issue to CWE-639 and CWE-862, and lists affected Langflow releases prior to 1.5.1 (with additional affected langflow-base criteria through 0.5.1). Version 1.5.1 corrects the logic by unconditionally applying the requester scope.

Defensive priority

High: prioritize immediate upgrade, secret review, and verification of flow ownership controls.

Recommended defensive actions

  • Upgrade Langflow to version 1.5.1 or later.
  • If you use langflow-base, ensure you are on a version outside the vulnerable range listed by NVD (through 0.5.1).
  • Review stored flows for embedded credentials or other secrets and rotate any exposed API keys or tokens.
  • Check access logs and recent flow changes for unauthorized reads, edits, or deletions.
  • Restrict access to affected instances until remediation is complete, especially in multi-user deployments.

Evidence notes

The supplied source corpus ties this CVE to the GitHub security advisory and patch PR referenced by NVD. NVD marks the record analyzed, assigns CVSS 8.7/HIGH, and lists CWE-639 and CWE-862. The provided dates indicate the CVE was published on 2026-03-27 and modified on 2026-05-11. No KEV entry is present in the supplied data.

Official resources

Publicly disclosed on 2026-03-27, which is the CVE published date provided in the source data. NVD later updated the record on 2026-05-11.