CVE-2026-17631: Langflow SSRF Vulnerability

CVE-2026-17631 Overview

CVE-2026-17631 is a Server-Side Request Forgery (SSRF) vulnerability affecting IBM Langflow OSS versions 1.0.0 through 1.10.2. A remote authenticated attacker can abuse the flaw to make the Langflow server issue arbitrary HTTP requests on their behalf. This allows access to sensitive information from internal network resources, cloud metadata services, or other systems reachable by the server. The weakness is classified under CWE-918: Server-Side Request Forgery.

Critical Impact
An authenticated attacker can coerce Langflow into requesting internal-only URLs, exposing confidential data such as cloud instance metadata, internal APIs, and non-public services.

Affected Products

Langflow Langflow OSS versions 1.0.0 through 1.10.2
Deployments on Apple macOS, Linux, and Microsoft Windows hosts
IBM-supported Langflow OSS distributions

Discovery Timeline

2026-09-04 - CVE-2026-17631 published to NVD
2026-09-09 - Last updated in NVD database

Technical Details for CVE-2026-17631

Vulnerability Analysis

Langflow is an open-source framework for building applications on top of large language models. The vulnerable code paths accept user-controlled URLs and dispatch outbound HTTP requests without adequate destination validation. An authenticated user with low privileges can supply a URL pointing to an internal endpoint the Langflow server can reach.

Because the server performs the request, network controls that block external clients do not apply. Attackers can enumerate internal services, retrieve responses, and extract sensitive content returned by those services. Impact is limited to information disclosure; the vulnerability does not directly permit data modification or denial of service.

Root Cause

The root cause is missing or insufficient validation of user-supplied URLs before Langflow issues an outbound request. The server does not enforce an allow-list of destinations, does not block requests to loopback, link-local, or private address ranges, and does not sanitize redirects. This aligns with the classic [CWE-918] SSRF pattern where trust is placed in a request origin rather than the request destination.

Attack Vector

Exploitation requires network access and valid authenticated credentials to the Langflow application. The attacker submits a component configuration, flow definition, or API request that contains an attacker-chosen URL. Langflow resolves and fetches that URL from its own network position.

Typical targets include cloud metadata endpoints such as http://169.254.169.254/latest/meta-data/, internal administration consoles, and unauthenticated services bound to 127.0.0.1. The returned response body or headers may be reflected back to the attacker through the Langflow interface, leaking credentials, tokens, or configuration data. Refer to the IBM Support advisory for vendor-specific technical details.

Detection Methods for CVE-2026-17631

Indicators of Compromise

Outbound HTTP requests from the Langflow process to 169.254.169.254, 127.0.0.1, or RFC 1918 address ranges that were not present before the vulnerable component was introduced.
Langflow application logs showing user-supplied URLs targeting metadata services, loopback, or internal-only hostnames.
Unexpected access entries in internal service logs where the source address matches the Langflow host.

Detection Strategies

Inspect Langflow request logs for URL parameters that resolve to private, loopback, or link-local IP ranges.
Correlate authenticated Langflow user sessions with anomalous outbound HTTP destinations from the server process.
Alert on responses containing cloud metadata keys such as iam/security-credentials or instance-identity being rendered back to a user session.

Monitoring Recommendations

Enable egress traffic logging on the Langflow host and forward events to a centralized analytics platform for review.
Baseline expected outbound destinations for Langflow and alert on deviations, especially requests to metadata IPs.
Audit Langflow user activity, focusing on newly created flows or components that reference external URL inputs.

How to Mitigate CVE-2026-17631

Immediate Actions Required

Upgrade Langflow to a version later than 1.10.2 that addresses CVE-2026-17631 as directed by the IBM Support advisory.
Restrict Langflow account provisioning and rotate credentials for any accounts that may have been misused.
Block outbound access from the Langflow host to cloud metadata endpoints and internal management interfaces at the network layer.

Patch Information

IBM has published remediation guidance for Langflow OSS in the IBM Support advisory for node 7285644. Administrators should consult the advisory for the specific fixed release and apply it across all Langflow instances running versions 1.0.0 through 1.10.2.

Workarounds

Place Langflow behind an egress proxy that enforces a destination allow-list and denies requests to private, loopback, and link-local ranges.
On cloud deployments, enforce IMDSv2 with hop-limit 1 to prevent metadata access through server-side request proxying.
Limit Langflow authentication to trusted users and enforce multi-factor authentication to reduce the pool of accounts capable of triggering the flaw.

bash

# Example: block AWS metadata service egress from the Langflow host using iptables
iptables -A OUTPUT -d 169.254.169.254 -j DROP
iptables -A OUTPUT -d 127.0.0.0/8 ! -o lo -j DROP
iptables -A OUTPUT -d 10.0.0.0/8 -m owner --uid-owner langflow -j DROP
iptables -A OUTPUT -d 172.16.0.0/12 -m owner --uid-owner langflow -j DROP
iptables -A OUTPUT -d 192.168.0.0/16 -m owner --uid-owner langflow -j DROP