Why is hash needed?

Question

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Hello! VKontakte has an "exit" button (link), some hash is stored in it, what is it for? After all, you can just make a page like this site.name/logoutand not write site.name/logout?hash=uegzywownbdheiwkxbthe fact that if I remove the hash or change the symbol, I will be redirected to the main page and yet, for some reason this hash is always the same. Why doesn't he change too?

Answer 1

this is protection against Cross-Site Request Forgery https://cheatsheetseries.owasp.org/cheatsheets/Cro...
this hash is generated per session. so it is checked when clicking that the click was made from the VK site, and not faked from another site