BitlBee OAuth
Although AFAIK the OAuth spec recommends supporting a mode for desktop apps where the provider just shows the user a code s/he should return to the program they're trying to authorize, not everyone seems to support this. In those cases, BitlBee uses this page to receive the code and show it to the user.
You may not like this for security reasons, but please complain to the service provider about that, not to the BitlBee authors. The code below expires in a short period of time or as soon as it's used once, which also limits the risk here.
Something went wrong while trying to authenticate with the OAuth provider: