CVE-2026-107366

Langflow message endpoints lack conversation ownership checks

IBM / Langflow · Langflow OSS

First documented disclosure · Review checkpoint

Summary

Message deletion or tampering, injected prompts and conversation-session takeover.

Severity and exploitation evidence

High · 8.3/10 · CVSS 3.1. Severity source.

Exploitation not established: The reviewed primary records do not establish malicious exploitation or a confirmed victim.

Exploitation evidence source

Technical severity is not a measure of observed attacks or of risk to your deployment. Attempts, demonstrations, and successful compromise retain the qualifications in the source.

How the weakness works

Three message operations omit ownership validation, allowing cross-user edits, deletion and session reassignment.

Conditions required

An authenticated user can address another user’s messages or session.

Potential impact

Message deletion or tampering, injected prompts and conversation-session takeover.

Affected versions and configurations

IBM lists Langflow OSS 1.0.0 through 1.12.4. This broad range conflicts with IBM’s issue-specific earlier-fix statement.

Fix and mitigation status

IBM says this issue was fixed in 1.9.0; 1.12.5 includes it. Its broad affected-version table still extends through 1.12.4.

Practical next steps

Upgrade to a current supported release containing the fix; back up the deployment and validate workflow behavior. Where MCP stdio is used, IBM additionally requires interpreter hardening and administrator-only controls; configuration changes do not replace upgrading.

Operating lesson

Bind every conversation mutation to its verified owner.

Evidence and limits

IBM bulletin 7293016 was initially published 2026-10-19; the CNA record followed on 2026-10-19. Earlier upstream patches are not assigned to this CVE by inference. Exact technical details absent from the public record remain unknown; a CVSS score is not an observed incident. The affected-range/earlier-fix inconsistency is preserved rather than silently reconciled.

Sources