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POST /users/v1/login previously returned two distinguishable error messages in the vulnerable branch: 'Username does not exist' when the username was not found, and 'Password is not correct for the given username' when it was found but the password did not match. This let an attacker enumerate valid usernames and use the login endpoint as a password oracle. Now both failure cases return the same generic 'Username or Password Incorrect!' message, matching the pattern used elsewhere in the code for the non-enumerable case, so the response no longer leaks whether the supplied username exists.
🏆 VAmPI — CTF Patch Score1 / 9 challenges patched
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Vulnerability
POST /users/v1/loginreturned two distinguishable failure messages:This lets an attacker enumerate valid usernames and use the endpoint as a password oracle (API2:2019 Broken User Authentication).
Fix
Both failure cases now return the same generic message ("Username or Password Incorrect!") regardless of whether the username exists, so the response no longer leaks account existence or password correctness separately.
Testing
Built and ran the app locally (WSL, vulnerable=1, DB seeded via /createdb):