FetLife: fetlife.com/signup_step_profile expose access_token of mapbox.com

Hi fetlife, I’m investigate on registration step on your site, in registration step at https://fetlife.com/signup_step_profile

when user type in field “private_location_name”

{F2652527}

it use frontend call to api.mapbox.com directly thus expose access_token, I was able to call it directly via command line:

curl 'https://api.mapbox.com/geocoding/v5/mapbox.places/ho%20chi.json?limit=10&types=place%2Clocality&autocomplete=true&language=en&access_token=pk.eyJ1IjoiZmV0bGlmZSIsImEiOiJjazhwMjNrajUwN2luM2xwcmxmMDNoajFoIn0.vge5GmfaG4OTyth8uS_N6w' \
  -H 'sec-ch-ua: "Chromium";v="116", "Not)A;Brand";v="24", "Google Chrome";v="116"' \
  -H 'Referer: https://fetlife.com/' \
  -H 'sec-ch-ua-mobile: ?0' \
  -H 'User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/116.0.0.0 Safari/537.36' \
  -H 'sec-ch-ua-platform: "Linux"' \
  --compressed

Upon having this access_token, I could freely use your token on my site, even though fetlife have Referer: https://fetlife.com/, I could navigate around that easily using direct http call from my server and inject Referer header as https://fetlife.com/.

Another issue (not security related), this request is for validating attribute unhandle email case yet :

curl 'https://fetlife.com/users/attributes/[email protected]' \
  -H 'sec-ch-ua: "Chromium";v="116", "Not)A;Brand";v="24", "Google Chrome";v="116"' \
  -H 'Accept: application/json' \
  -H 'Referer: https://fetlife.com/signup_step_profile' \
  -H 'X-CSRF-Token: WbVVfdWFF2nIoWJ7yJHpjVMtt1i1_VFMTpDyq4dRI72NG3onq_MOtQmhHXD6nlD-aKAYoqpvAhCAWu8z6zf_qQ' \
  -H 'sec-ch-ua-mobile: ?0' \
  -H 'User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/116.0.0.0 Safari/537.36' \
  -H 'sec-ch-ua-platform: "Linux"' \
  --compressed

500 Internal Server Error
If you are the administrator of this website, then please read this web application's log file and/or the web server's log file to find out what went wrong.%

Another issue I see there is two authenticity_token on registration hidden input, I believe this is a mistake (?)

{F2652528}

Impact

exposing access_token on mapbox give me freely use of your resources (I use, you pay).