AlpacaHack Logo

Tag: Authentication Bypass

Sign InSign Up

Authentication Bypass

No description is available for this tag.

Updated May 3, 2026
Authentication Bypass Challenges
Xmas Login
hiikunz

hiikunz

Web
375 solves
I wanna be the Admin
tchen

tchen

Web
296 solves
🍪
minaminao

minaminao

Web
Beginner
183 solves
Stateless Auth
tchen

tchen

Web
174 solves
Another Login Challenge
tchen

tchen

Web
135 solves
One More Login Challenge
tchen

tchen

Web
129 solves
ding-dong-ting-ping

yoshiking

Crypto
10 solves

One More Login Challenge

Daily AlpacaHackTopic: MongoDBReleased: Apr 16, 2026

129 solves
Web

by

tchen

tchen

Login again?! (Note: You don't necessarily have to solve Another Login Challenge first)

Beginner Hint 1: Overview of the Challenge
  • In index.js, a simple login feature is implemented.
  • It appears to use MongoDB to check whether a user with the submitted username and password exists.
  • It does not seem possible to create your own user. Also, a user called admin is registered, but guessing that password would be impossible.
Beginner Hint 2: How to Approach the Challenge
  • As mentioned in the comments, it seems possible to send data in both application/x-www-form-urlencoded and application/json formats. Therefore, if you use JSON, you can send non-string values in username and password.
  • The login form alone might not allow you to send the intended data. For methods of sending data without using a browser, refer to my writeup for I wanna be the Admin.
Beginner Hint 3: When you are really stuck
  • Try searching for MongoDB injection or NoSQL injection.
one-more-login-challenge.tar.gz
descriptionsolveswriteups