CVE-2026-55423: Langflow Auth Bypass Vulnerability

CVE-2026-55423 Overview

CVE-2026-55423 is a session management vulnerability in Langflow, an open-source tool for building and deploying AI-powered agents and workflows. In versions prior to 1.7.0, the logout button fails to invalidate the active session. The previously authenticated user remains logged in until another user explicitly authenticates on the same client. This flaw is classified under CWE-613: Insufficient Session Expiration. The issue is fixed in Langflow 1.7.0.

Critical Impact
A user who believes they have logged out remains authenticated, allowing anyone with subsequent physical access to the client to interact with the Langflow application under the previous user's identity.

Affected Products

Langflow versions prior to 1.7.0
Langflow deployments exposing the web UI on shared or multi-user clients
Langflow self-hosted instances accessed from shared workstations

Discovery Timeline

2026-06-23 - CVE-2026-55423 published to NVD
2026-06-24 - Last updated in NVD database

Technical Details for CVE-2026-55423

Vulnerability Analysis

The vulnerability stems from incomplete client-side and server-side session termination logic in the Langflow logout workflow. When a user clicks the logout button, the application removes the user-facing indicators of an authenticated session but does not invalidate the underlying session token or clear stored credentials. The session remains valid on the server until it is naturally expired or overwritten by a new login on the same client.

This behavior is characteristic of CWE-613: Insufficient Session Expiration, where the application accepts session identifiers after their intended termination. The vendor addressed the issue in GitHub Pull Request #10527 and GitHub Pull Request #10528, with details published in the GitHub Security Advisory GHSA-7hw8-6q6r-4276.

Root Cause

The root cause is that the logout handler in Langflow does not perform server-side session invalidation. The session token and any cached authentication state persist beyond the user-initiated logout event. Without an explicit token revocation step, the previous user's identity continues to authorize requests to the Langflow API and UI.

Attack Vector

Exploitation requires physical or local access to the client device where the previous user logged out. An attacker reaching the unattended workstation can navigate to the Langflow interface and operate under the prior user's session. The attacker can view, modify, or execute AI workflows and agents accessible to that account. No credentials, social engineering, or network position are required.

No public proof-of-concept exploit is associated with this CVE, and it is not listed in the CISA Known Exploited Vulnerabilities catalog.

Detection Methods for CVE-2026-55423

Indicators of Compromise

Langflow user activity originating from a session after the user reports logging out
Workflow modifications, agent executions, or API calls attributed to an account during periods when the legitimate user was not present
Authentication audit logs lacking a corresponding session-invalidation event after a logout action

Detection Strategies

Review Langflow application logs to confirm that logout events generate a corresponding session-termination record on the server
Correlate UI logout events with subsequent API activity on the same session token to surface persistence beyond logout
Inventory Langflow deployments and verify installed version is 1.7.0 or later using package metadata

Monitoring Recommendations

Monitor session duration metrics for accounts on shared or kiosk-style workstations where Langflow is accessed
Alert on Langflow API requests bearing session tokens that should have been invalidated according to user actions
Track failed remediation by scanning container images and Python environments for Langflow versions below 1.7.0

How to Mitigate CVE-2026-55423

Immediate Actions Required

Upgrade Langflow to version 1.7.0 or later, which contains the official fix
Restart all Langflow services after upgrading to force re-authentication and invalidate residual sessions
Instruct users on shared workstations to close the browser entirely after using Langflow until upgrades are complete

Patch Information

The vulnerability is fixed in Langflow 1.7.0. The corrective changes are tracked in GitHub Pull Request #10527 and GitHub Pull Request #10528. Refer to the GitHub Security Advisory GHSA-7hw8-6q6r-4276 for the authoritative remediation guidance.

Workarounds

Restrict Langflow access to single-user workstations until the upgrade is applied
Configure shorter server-side session timeouts to reduce the exposure window after a missed logout
Require users to close the browser session after using Langflow on any shared device

bash

# Upgrade Langflow to the patched release
pip install --upgrade "langflow>=1.7.0"

# Verify the installed version
python -c "import langflow; print(langflow.__version__)"