alt Hacker NewsCan someone explain why people struggle with CORS?
The full strength of the SOP applies by default. CORS is an insecurity feature that relaxes the SOP. Unless you need to relax the SOP, you shouldn't be enabling CORS, meaning you shouldn't be sending an Access-Control-Allow-Origin header at all.
If your front-end at www.example.com makes calls to api.example.com, then it's simple enough to just add www.example.com to CORS.
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That simple prod example isn't where people struggle with CORS. It's during development and I've got assets on Cloudflare and AWS and GCP and localhost:3000 and localhost:8000, and localhost:3001 and then a VM in Hetner at API.example.com because why not, that shit gets complicated and people get confused and lost. I mean, yeah, don't do that, but CORS gets complicated once the project gets enough teams involved.
IME, CORS is pretty straightforward in prod but can be a huge pain in dev environments, so you end up with lots of little hacks to get your dev environments working (and then one of those hacks leaks back into prod and now you have CORS problems in prod).