CVE-2026-7869: IBM Langflow Path Traversal Vulnerability

CVE-2026-7869 Overview

CVE-2026-7869 is a path traversal vulnerability [CWE-22] in IBM Langflow OSS versions 1.0.0 through 1.10.3. The flaw exists in the Knowledge Bases API endpoint POST /api/v1/knowledge_bases. User-supplied knowledge base names are passed directly into filesystem path construction without sanitization or containment checks. An authenticated attacker can traverse outside the intended storage directory to create arbitrary directories and write files anywhere the Langflow process has permissions.

Critical Impact
Authenticated attackers can write arbitrary files outside the knowledge base directory, potentially enabling configuration tampering, log poisoning, or code drop attacks against the host running Langflow.

Affected Products

IBM Langflow OSS 1.0.0
IBM Langflow OSS versions 1.0.1 through 1.10.2
IBM Langflow OSS 1.10.3

Discovery Timeline

2026-08-05 - CVE-2026-7869 published to NVD
2026-08-05 - Last updated in NVD database

Technical Details for CVE-2026-7869

Vulnerability Analysis

The vulnerability resides in the Knowledge Bases creation workflow exposed at POST /api/v1/knowledge_bases. When a client submits a request containing a knowledge base name, Langflow uses that value as a path component when creating the backing directory on disk. The application does not normalize the input, reject traversal sequences such as ../, or verify that the resolved path stays within the designated knowledge base root.

An authenticated user can send a crafted name value containing traversal sequences or absolute path fragments. The server then invokes directory creation and file writes against the attacker-chosen location. Impact is bounded by the filesystem privileges of the Langflow service account, which in typical container or virtual environment deployments still permits writes to application code, configuration, and log directories.

Because exploitation requires authentication, the attack surface is limited to users with valid credentials or sessions. However, Langflow deployments frequently permit low-privilege or self-registered users, reducing this barrier in practice.

Root Cause

The root cause is missing input validation on the knowledge base name parameter. The code constructs a filesystem path by concatenating the base storage directory with user input rather than treating the name as an opaque identifier and mapping it to a safe internal path. No canonicalization check compares the resolved path against the intended parent directory.

Attack Vector

Exploitation is performed over the network against the Langflow HTTP API. The attacker authenticates, then issues a POST /api/v1/knowledge_bases request with a name field containing traversal payloads such as ../../etc/langflow/ or similar sequences targeting sensitive directories. The server creates the directory and, on subsequent write operations tied to the knowledge base, drops files at the attacker-controlled location. See the IBM Support Page for vendor details.

Detection Methods for CVE-2026-7869

Indicators of Compromise

Unexpected directories appearing outside the configured Langflow knowledge base storage root, especially in /etc, /var, application install paths, or user home directories.
Langflow application logs showing POST /api/v1/knowledge_bases requests where the name field contains ../, ..\, URL-encoded traversal sequences, or absolute path prefixes.
New or modified files owned by the Langflow service account in directories the application should never write to.

Detection Strategies

Inspect HTTP access logs and API gateway telemetry for requests to /api/v1/knowledge_bases with suspicious name values, including encoded variants such as %2e%2e%2f.
Enable filesystem auditing (auditd on Linux) on directories adjacent to the Langflow storage root to alert on directory creation by the Langflow process outside its expected working set.
Correlate authenticated API activity with filesystem changes to identify users creating knowledge bases that resolve to non-standard paths.

Monitoring Recommendations

Baseline the legitimate paths under the Langflow knowledge base directory and alert on deviations.
Forward Langflow application and web server logs to a centralized log platform and apply detections for traversal patterns in API request bodies.
Monitor for privilege-adjacent side effects, including modifications to Langflow configuration files, startup scripts, or Python site-packages under the service account.

How to Mitigate CVE-2026-7869

Immediate Actions Required

Upgrade IBM Langflow OSS to a version later than 1.10.3 that includes the vendor fix, as referenced on the IBM Support Page.
Restrict access to the Langflow API to trusted, authenticated users and remove any anonymous or self-service registration paths that expose the Knowledge Bases endpoint.
Audit the Langflow filesystem for directories or files created outside the expected knowledge base storage root and investigate any anomalies.

Patch Information

IBM has published guidance for this vulnerability on the IBM Support Page. Administrators should apply the fixed release identified by IBM and confirm the deployed version is no longer in the affected 1.0.0 through 1.10.3 range.

Workarounds

Run Langflow under a dedicated low-privilege service account with a restrictive umask and no write access to system directories.
Deploy Langflow inside a container with a read-only root filesystem and a writable volume mounted only at the knowledge base storage path.
Place a reverse proxy or web application firewall in front of Langflow and block requests to /api/v1/knowledge_bases that contain ../, ..\, or encoded traversal sequences in the request body.

bash

# Example reverse proxy rule to block traversal payloads in knowledge base names
# (nginx snippet; adapt to your environment)
location /api/v1/knowledge_bases {
    if ($request_body ~* "(\.\./|\.\.\\|%2e%2e%2f|%2e%2e/)") {
        return 400;
    }
    proxy_pass http://langflow_upstream;
}