Executive Intelligence Brief
A critical IDOR vulnerability, CVE-2026-33760, was discovered in Langflow, a tool for building and deploying AI-powered agents and workflows. This vulnerability has a CVSS score of 8.8 and allows any authenticated user to read, modify, or permanently delete another user's data. The vulnerability is fixed in Langflow version 1.9.0. Organizations should immediately upgrade to version 1.9.0 or later to mitigate this vulnerability.
Threat Overview
Langflow is a tool for building and deploying AI-powered agents and workflows. It has a significant deployment footprint in the AI and machine learning communities. Prior to version 1.9.0, Langflow's /api/v1/monitor router exposed 7 endpoints that performed read, write, and delete operations on user-owned resources without verifying that the authenticated requester owned the targeted resource. This is a classic IDOR/BOLA (Broken Object Level Authorization) vulnerability.
Technical Deep Dive
Vulnerability Classification
The vulnerability is classified as CWE-639, which is an Insecure Direct Object Reference (IDOR) vulnerability. This class of vulnerability occurs when an application uses user-supplied input to directly access an object or resource without properly verifying the user's authorization to access that object.
Root Cause Analysis
The root cause of this vulnerability is the inconsistent application of ownership checks in the /api/v1/monitor router. While one endpoint in the same source file (monitor.py) correctly implemented an ownership check, the other 7 endpoints did not, allowing an authenticated user to access and manipulate another user's resources by supplying the target's resource ID or flow_id.
Attack Vector & Chain
The attack vector for this vulnerability is network-based (AV:N), with a low attack complexity (AC:L) and low privileges required (PR:L). No user interaction (UI:N) is needed, and the scope of the vulnerability is unchanged (S:U). The confidentiality, integrity, and availability impacts are all high (C:H/I:H/A:H).
Exploitation Scenario Walkthrough
Scenario: Unauthorized Data Access and Manipulation via IDOR
Reconnaissance: An attacker discovers that Langflow is being used by a target organization and identifies the /api/v1/monitor router as a potential attack surface.
Weaponization: The attacker prepares by obtaining a valid authenticated session or token to access the Langflow application.
Delivery & Exploitation: The attacker sends a request to one of the vulnerable endpoints in the /api/v1/monitor router, supplying the resource ID or flow_id of another user's data. The server processes the request without verifying ownership, allowing the attacker to read, modify, or delete the targeted resource.
Post-Exploitation: The attacker may use the accessed data for malicious purposes, such as data exfiltration, or manipulate the resources to disrupt the target user's workflows.
Impact Realization: The final impact is the unauthorized access, modification, or deletion of user data, leading to potential data breaches, workflow disruptions, and reputational damage.
Exploitation in the Wild
This vulnerability is not currently being actively exploited in the wild. However, given its severity and the ease of exploitation, there is a high likelihood that attackers will target this vulnerability in the future.
Impact Analysis
Direct Impact
The direct impact of this vulnerability is the potential for unauthorized data access, modification, or deletion. An attacker can achieve read, write, and delete operations on user-owned resources, including messages, sessions, build artifacts, and LLM transaction logs.
Downstream & Cascading Effects
The downstream effects of this vulnerability include potential data breaches, workflow disruptions, and reputational damage. Additionally, there may be regulatory implications if sensitive data is exposed or manipulated.
Affected Products & Versions
The affected product is Langflow, and the affected versions are prior to 1.9.0. The vulnerability is fixed in Langflow version 1.9.0.
Detection & Threat Hunting
Indicators of Compromise
Indicators of compromise (IoCs) for this vulnerability may include unusual patterns of access to the /api/v1/monitor router, suspicious changes to user data, or anomalies in workflow execution.
Detection Rules & Signatures
Detection rules may include monitoring for requests to the /api/v1/monitor router with suspicious parameters, such as resource IDs or flow_ids that do not match the authenticated user's data. Behavioral patterns that indicate exploitation include unexpected data modifications or deletions.
Threat Hunting Queries
Threat hunting queries may include searching for requests to the /api/v1/monitor router with elevated privileges, monitoring for changes to user data that do not align with normal workflow patterns, and identifying anomalies in access patterns to Langflow resources.
Remediation & Hardening
Immediate Actions (0-24 hours)
The immediate action is to upgrade Langflow to version 1.9.0 or later. This patch fixes the IDOR vulnerability and ensures that ownership checks are consistently applied to all endpoints in the /api/v1/monitor router.
Short-Term Hardening (1-7 days)
In the short term, additional security controls may include implementing Web Application Firewalls (WAFs) to detect and prevent suspicious requests to the /api/v1/monitor router, enhancing monitoring and logging to detect anomalies, and restricting access to sensitive resources.
Strategic Recommendations
Strategic recommendations include implementing robust authorization and access control mechanisms, conducting regular security audits and penetration testing, and ensuring consistent application of security best practices across all components of the Langflow application.
Analyst Assessment
The risk of this vulnerability is high due to its severity, ease of exploitation, and potential impact. Organizations should prioritize upgrading to Langflow version 1.9.0 or later and implement additional security controls to prevent and detect potential attacks.
Sources
- National Vulnerability Database (NVD) - CVE-2026-33760