Flowise CVE-2026-46440

Requires network reachability to the Flowise HTTP service and an exposed checkBasicAuth endpoint on a Flowise deployment running version 3.1.1 or earlier that was started with FLOWISE_USERNAME and FLOWISE_PASSWORD environment variables configured (basic auth mode for simpler deployments per the GHSA). No authentication or user interaction is needed to attempt the attack, but successful compromise is limited by the strength and entropy of the operator-chosen FLOWISE_PASSWORD - a long randomized password makes brute-force infeasible even without rate limiting, while default or weak operator passwords make exploitation trivial. Exploitation is further bounded to instances where the auth endpoint is network-reachable by the attacker (not behind a VPN or IP allowlist).

The CVSS 3.1 score of 9.1 (AV:N/AC:L/PR:N/UI:N/C:H/I:H/A:N) reflects unauthenticated network reachability with high confidentiality and integrity impact once credentials are guessed, but this score arguably overstates real-world risk: actual compromise still requires guessing or brute-forcing the operator-configured FLOWISE_PASSWORD, and CISA's SSVC assessment marks Automatable as 'no' with Exploitation only at 'poc' stage. EPSS is correspondingly low at 0.04% (13th percentile), the CVE is not on CISA KEV, and the GHSA itself rates severity as Medium rather than Critical. The practical priority therefore depends on deployment hygiene - instances exposing checkBasicAuth to the internet with weak FLOWISE_PASSWORD values are at meaningful risk of credential stuffing and timing-based enumeration, while instances behind a VPN or with a strong randomized password face limited exposure. Note the disconnect between the NVD 9.1 score and the vendor's Medium rating; defenders should weight the SSVC/EPSS signals when prioritizing.

An attacker discovers an internet-exposed Flowise instance via Shodan or similar reconnaissance, then issues a high-volume scripted POST loop to the checkBasicAuth endpoint with common username/password pairs and operator-style defaults. Because no rate limiting is in place and response strings differ between success and failure, the attacker can both enumerate valid usernames and confirm a successful guess, then log in to access workflows, prompts, and any stored credentials inside Flowise.