CVE-2026-12767 Overview
CVE-2026-12767 is a Server-Side Request Forgery (SSRF) vulnerability affecting IBM Langflow OSS versions 1.0.0 through 1.11.5. The flaw allows an unauthenticated remote attacker to coerce the server into issuing arbitrary outbound HTTP requests. Attackers can leverage this behavior to enumerate internal network resources, reach services behind the perimeter, or stage follow-on attacks against reachable systems. The weakness is classified under [CWE-918] Server-Side Request Forgery. IBM published an advisory referenced in the IBM Support Node Documentation.
Critical Impact
An unauthenticated attacker can pivot the vulnerable Langflow instance into internal networks, potentially reaching cloud metadata endpoints, admin interfaces, and other services that trust internal callers.
Affected Products
- IBM Langflow OSS 1.0.0 through 1.11.5
- Deployments exposing the Langflow HTTP interface to untrusted networks
- Container and self-hosted Langflow installations built from affected OSS releases
Discovery Timeline
- 2026-09-14 - CVE-2026-12767 published to the National Vulnerability Database
- 2026-09-16 - Last updated in NVD database
Technical Details for CVE-2026-12767
Vulnerability Analysis
IBM Langflow OSS is a visual framework for building applications with large language models. The vulnerability arises in request-handling logic that accepts a user-supplied URL and fetches remote content without validating the target host or scheme. Because the endpoint requires no authentication, any network-reachable attacker can submit crafted requests. The Langflow process then initiates outbound connections on the attacker's behalf, revealing internal service responses or side-effect behavior. Impact is bounded to confidentiality and integrity of information the server can reach; the CVSS vector indicates no direct availability impact.
Root Cause
The root cause is missing or insufficient validation of destination URLs supplied to a server-side fetch primitive. The affected code path does not enforce an allowlist of hostnames, block private and link-local address ranges, or restrict URL schemes to safe protocols. This is a classic instance of [CWE-918], where trust in a client-controlled URL is extended to the server's network position.
Attack Vector
Exploitation is performed over the network with low complexity and no authentication or user interaction. An attacker sends an HTTP request to a Langflow API endpoint that accepts a URL parameter, substituting internal targets such as http://169.254.169.254/latest/meta-data/ on cloud instances or http://localhost:<port>/ for co-resident admin services. The server executes the request and returns or acts on the response. No verified public proof-of-concept code has been published; refer to the IBM Support Node Documentation for vendor technical details.
Detection Methods for CVE-2026-12767
Indicators of Compromise
- Outbound HTTP requests from the Langflow host to RFC1918, loopback, or link-local addresses that do not match baseline behavior.
- Requests from the Langflow process to cloud instance metadata endpoints such as 169.254.169.254 or metadata.google.internal.
- Unusual spikes in unauthenticated API calls containing URL-shaped parameters targeting Langflow endpoints.
Detection Strategies
- Inspect web server and reverse proxy logs for unauthenticated requests to Langflow API paths carrying URL query or body parameters.
- Correlate inbound API activity with subsequent outbound connections initiated by the Langflow process to detect SSRF chains.
- Deploy egress filtering telemetry to flag any Langflow-originated traffic destined for internal management or metadata subnets.
Monitoring Recommendations
- Enable verbose access logging on the Langflow application and forward logs to a centralized analytics platform.
- Alert on any Langflow outbound connection to non-approved destinations, including private IP space and cloud metadata addresses.
- Track process-level network telemetry to attribute outbound requests to the Langflow runtime rather than co-hosted services.
How to Mitigate CVE-2026-12767
Immediate Actions Required
- Upgrade IBM Langflow OSS to a fixed release above 1.11.5 as identified in the IBM Support Node Documentation.
- Restrict network exposure of Langflow to trusted operators and remove any public-internet accessibility.
- Block outbound access from the Langflow host to cloud metadata endpoints and internal management networks at the firewall layer.
Patch Information
IBM has published remediation guidance in the IBM Support Node Documentation. Administrators should follow the vendor advisory to obtain the fixed version and apply it to all affected deployments, including container images built from vulnerable base tags.
Workarounds
- Place Langflow behind an authenticating reverse proxy that rejects unauthenticated requests to URL-accepting endpoints.
- Enforce an egress allowlist so the Langflow process cannot reach internal, loopback, or link-local addresses.
- On cloud instances, require Instance Metadata Service v2 (IMDSv2) and block IMDSv1 to reduce the value of SSRF against metadata endpoints.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
