MCP OAuth2 authentication code and implicit problems

Bug Reports
1

Describe the Bug

OAuth2 authorization code callback to the cursor app does not work. The redirect url is correct. Tried to change to implicit, but Cursor seems not to support it (it stops after the registration call and then sends an empty request to the authorization server). How to get authentication working ?

Steps to Reproduce

  1. implement OAUTH dynamic client registration (Cursor sees this as mandatory, it should not) authorization should be possible by an already created client on the authorization server with secret and id.
  2. Add the MCP.json to cursor
  3. Cursor calls the Oauth2 endpoint and request for a login (only “code” works)
  4. Click login, browser opens the login page
  5. Click submit to launch the redirect url.
  6. Ubuntu cannot launch cursor.

Expected Behavior

  1. Ubuntu to launch cursor and cursor to send a code for token exchange request

Screenshots / Screen Recordings

Operating System

Linux

Current Cursor Version (Menu → About Cursor → Copy)

Version: 1.1.7
VSCode Version: 1.96.2
Commit: 7111807980fa9c93aedd455ffa44b682c0dc1350
Date: 2025-07-01T07:30:30.003Z
Electron: 34.5.1
Chromium: 132.0.6834.210
Node.js: 20.19.0
V8: 13.2.152.41-electron.0
OS: Linux x64 6.15.3

Does this stop you from using Cursor

Yes - Cursor is unusable

2

Interestingly, not completing the login process, but then disable /enable the service with the blue slider, shows up the the tools and a logout button. That should not be possible.

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image837×212 9.18 KB

P.S: Even these tool/functions now show up, it seem there isn’t a way to call the tool ?

3

what are you using for your mcp.json file?