Flowise: Unauthenticated OAuth2 token refresh endpoint returns access tokens — enables token theft for any connected service

Flowise is a drag & drop user interface to build a customized large language model flow. Prior to 3.1.3, the POST /api/v1/oauth2-credential/refresh/:credentialId endpoint is included in WHITELIST_URLS and requires no authentication. The endpoint decrypts the stored credential, sends a refresh request to the configured OAuth provider with the client secret and refresh token, and returns the refreshed access_token in the response body. An attacker with a credential ID can use the token to access the victim's connected service and can also exhaust refresh-token quota. This issue is fixed in 3.1.3.

Source published

4 Aug 2026 19:37:22 UTC

Source modified

5 Aug 2026 19:05:33 UTC

Observed here

23 Oct 2026 15:48:27 UTC

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CVSS 4.0 · 9.2 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:H/SI:L/SA:N