CVE-2026-18891

CVE-2026-18891 is an improper authentication flaw (CWE-287) in IBM Langflow OSS versions 1.0.0 through 1.11.1 in which the application fails to properly verify callers before granting access. Because the attack vector is network-based with no privileges or user interaction required (CVSS 3.1: 8.2), a remote unauthenticated attacker can trigger the flaw directly against any reachable Langflow instance. A successful attacker can execute arbitrary flows and access sensitive information processed by the platform, potentially exposing data handled through its AI workflow capabilities. Anyone running an affected Langflow OSS release — self-hosted, containerized, or exposed via its web/API interface — is affected. Exploitation has not been reported: the flaw is not in CISA KEV, no public proof-of-concept is known, and EPSS currently estimates only a 0.3% chance of exploitation within 30 days.

What to do: Upgrade Langflow OSS to a fixed release beyond 1.11.1 when available and monitor IBM's advisory for the patched version. Until patched, restrict access to the Langflow web/API interface to trusted networks, verify authentication is enforced on any externally reachable instance, and review logs for unexpected flow executions.