CVE-2026-13442 Overview
CVE-2026-13442 affects IBM Langflow OSS versions 1.0.0 through 1.10.1. The vulnerability allows an authenticated attacker to reuse another user's FAISS (Facebook AI Similarity Search) namespace. This access exposes owner-only vector content and enables manipulation of downstream query results. The flaw maps to [CWE-520] and results in cross-user information disclosure combined with limited integrity impact through persistent poisoning of retrieval-augmented generation (RAG) responses.
Critical Impact
An authenticated attacker on the network can access vector store data belonging to other users and poison query outputs returned by the affected Langflow instance.
Affected Products
- IBM Langflow OSS 1.0.0 through 1.10.1
- FAISS-backed vector store components within Langflow
- Multi-tenant Langflow deployments exposing shared namespaces
Discovery Timeline
- 2026-07-28 - CVE-2026-13442 published to NVD
- 2026-07-30 - Last updated in NVD database
Technical Details for CVE-2026-13442
Vulnerability Analysis
IBM Langflow OSS integrates FAISS as a vector database backend for embedding storage and similarity search. The application fails to enforce owner-based access control over FAISS namespaces. An authenticated user can reference a namespace belonging to another user and retrieve or modify its contents.
This flaw enables two attack outcomes. First, an attacker reads vector content owned by another tenant, exposing embedded documents and derived context. Second, the attacker writes crafted vectors into a shared namespace, poisoning results returned to the legitimate owner during subsequent RAG queries.
Root Cause
The root cause is an authentication and authorization gap classified under [CWE-520] (.NET Misconfiguration: Use of Impersonation). In this context, the deployment lacks per-user isolation on FAISS namespace identifiers. Namespace references act as bearer identifiers without owner verification, allowing horizontal privilege escalation across tenants.
Attack Vector
The attack requires network access and low-privilege authenticated credentials to the Langflow instance. No user interaction is needed. An attacker enumerates or guesses namespace identifiers, then issues vector read or write operations against another user's namespace through the Langflow API. Poisoned entries persist in the vector store and influence future query responses returned to victims.
Refer to the IBM Support Page for vendor technical details.
Detection Methods for CVE-2026-13442
Indicators of Compromise
- Access log entries showing a single authenticated user referencing FAISS namespace identifiers associated with multiple other users.
- Unexpected write operations, index rebuilds, or embedding uploads targeting namespaces the acting user does not own.
- Anomalous RAG query outputs containing content unrelated to the requesting user's stored documents.
Detection Strategies
- Instrument Langflow API endpoints to log namespace identifiers alongside authenticated principals and alert on mismatches.
- Correlate vector store mutations with the acting user identity to surface cross-tenant writes.
- Baseline query result content per user and flag drift consistent with poisoned embeddings.
Monitoring Recommendations
- Forward Langflow application and access logs to a centralized analytics platform for retention and query.
- Monitor authentication events for low-privilege accounts performing high-volume namespace enumeration.
- Track FAISS index file changes on disk and alert on modifications outside expected owner processes.
How to Mitigate CVE-2026-13442
Immediate Actions Required
- Upgrade IBM Langflow OSS to a version above 1.10.1 that addresses the namespace isolation defect, as directed by the IBM advisory.
- Restrict network access to Langflow instances so only trusted authenticated users can reach the API surface.
- Rotate credentials for any Langflow accounts that may have been used to access unauthorized namespaces.
- Audit existing FAISS namespaces for unauthorized entries and rebuild indexes from trusted sources where poisoning is suspected.
Patch Information
Consult the IBM Support Page for the fixed version and remediation guidance. Apply the vendor-supplied update to all Langflow deployments running versions 1.0.0 through 1.10.1.
Workarounds
- Deploy Langflow in single-tenant configurations until the patch is applied, eliminating cross-user namespace exposure.
- Segment users into isolated Langflow instances or containers so FAISS namespaces cannot be referenced across tenants.
- Enforce strict authentication and network-layer access controls, including per-user API tokens with restricted scope.
# Configuration example: restrict Langflow to loopback until patched
export LANGFLOW_HOST=127.0.0.1
export LANGFLOW_PORT=7860
export LANGFLOW_AUTO_LOGIN=false
export LANGFLOW_SUPERUSER_PASSWORD="<rotated-strong-secret>"
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
