Daily AlpacaHack

A daily CTF challenge with a fun new puzzle every day

What is Daily AlpacaHack?

We publish one simple, beginner-friendly or educational CTF challenge every day!

Join Anytime

Solve within 24 hours of release to appear on the leaderboard.

Not a Competition

Discussion with friends or AI is welcome (account sharing is prohibited).

Solution Sharing Rules

Sharing solutions is allowed only after 24 hours have passed since release.

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Today's Challenge

Submissions (latest 3)

nomeaning

SOLVED!

May 9, 5:39 PM

tadanobutubutu

SOLVED!

May 9, 5:32 PM

edwowmath

SOLVED!

May 9, 5:01 PM

Leaderboard

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Try the first challenge

Is this your first CTF? Let's begin by tackling the first challenge released on Daily AlpacaHack.

Upcoming challenges reveal the , , and in advance.

May 2026

Solved

Unsolved

Upcoming

Mon

Tue

Wed

Thu

Fri

Sat

Sun

shiragi

Unrevealed TXT

Misc

Easy

123 solves

serioton

unheard

Misc

Medium

73 solves

minaminao

permission denied

Misc

Hard

76 solves

minaminao

permission denied 2

Misc

Medium

75 solves

admin

Alpaca++

Misc

Welcome

181 solves

tchen

Alpaca Rangers 2

Web

Easy

157 solves

pppp4649

Small N

Crypto

Easy

120 solves

hiikunz

secret-table-2

Web

Medium

119 solves

serioton

do the math

Misc

Medium

100 solves

trimscash

func-array

Pwn

Easy

111 solves

minaminao

permission denied 3

Misc

Medium

101 solves

baumroll1234

Vending Machine

Misc

Easy

134 solves

hiikunz

reused n

Crypto

Medium

93 solves

rsk0315

Bounds Checking

Pwn

Hard

15 solves

serioton

Planned topicLFSR

Rev

Easy

minaminao

Planned topicDocker

Misc

Medium

Coming soon

k0080

Planned topicProcedure Linkage Table

Pwn

Hard

Coming soon

k0080

Planned topicCUDA

Rev

Hard

Coming soon

ptr-yudai

Planned topicStack

Pwn

Hard

Want a harder challenge?

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Writeups

Writeup for reused n tadanobutubutu ja reused n 34 minutes ago
Writeup for reused n baumroll1234 ja reused n 1 hour ago
Writeup for Daily AlpacaHack 5/3-5/9 kakur41 ja reused n +6 2 hours ago
Writeup for reused n goroshirow ja reused n 2 hours ago
Writeup for Vending Machine baumroll1234 author ja Vending Machine 4 hours ago
Writeup for Vending Machine tadanobutubutu ja Vending Machine 7 hours ago
Daily AlpacaHackに挑戦するつくよみちゃん 05/08 misc/Vending Machine/baumroll1234 tsukuyomi-chan ja Vending Machine 8 hours ago
Daily AlpacaHackに挑戦するつくよみちゃん 05/07 misc/Permission Denied 3/minaminao tsukuyomi-chan ja permission denied 3 8 hours ago
Writeup for Vending Machine nozokare ja Vending Machine 9 hours ago
Writeup for permission denied 3 nozokare ja permission denied 3 9 hours ago

Rows:

Bounds Checking

Topic: Out-of-Bounds WriteReleased: May 10, 2026

15 solves

Pwn

Hard

rsk0315

It is safe because the index is in-bounds!

bounds-checking.tar.gz

description solves