CVE-2026-70636

Flowise through version 3.1.4 contains an authentication bypass (CWE-862) caused by prefix-based whitelist matching in the authentication middleware defined in packages/server/src/utils/constants.ts. An unauthenticated attacker can send a POST request to the OAuth2 credential refresh route with a trailing credential identifier, which slips past the whitelist check and bypasses all authentication and authorization controls. This triggers unauthorized OAuth token rotation against credentials belonging to any workspace, and the repeated forced refreshes can disrupt or invalidate dependent OAuth integrations relying on those credentials. The flaw affects any self-hosted Flowise deployment up to and including 3.1.4 where the server API is reachable by untrusted parties, and it is a bypass of the incomplete fix for CVE-2026-41273. A public proof-of-concept write-up exists, EPSS is currently low (0.4%), and there is no evidence of exploitation in the wild or a CISA KEV listing.

What to do: Upgrade Flowise to a version newer than 3.1.4 that corrects the middleware whitelist matching (verify the fix notes reference CVE-2026-70636, since 3.1.4's fix for CVE-2026-41273 is insufficient). Until patched, restrict network access to the Flowise server API (bind to internal interfaces, enforce VPN/IP allowlisting, and require an auth proxy) and treat previously configured OAuth2 credentials as potentially rotated by an attacker — review refresh/audit logs for unexpected token rotations and re-authorize any dependent OAuth integrations that break.