PaperMC / PaperMC/Paper

[ MC-299193 | VANILLA EXPLOIT ] Crossbow cooldown bypass

Open
#13,113 4 comments 0 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

status: needs triage version: 1.21.8
Dominant language
Java
Stars
12.7k
Forks
3.5k
Avg merge
3d 13h
Merged PRs (30d)
11

Description

Expected behavior

Crossbow should consistently enter cooldown when a projectile is charged

Observed/Actual behavior

Crossbow is charged without triggering the cooldown

Steps/models to reproduce

https://github.com/user-attachments/assets/6ab30688-a7fa-4b0b-b967-da4b0434f328

Let go of the use button right as the charge animation is about to complete.

Plugin and Datapack List

None

Paper version

This server is running Paper version 1.21.8-60-main@29c8822 (2025-09-06T21:49:13Z) (Implementing API version 1.21.8-R0.1-SNAPSHOT)
You are running the latest version
Previous version: 1.21.7-32-e792779 (MC: 1.21.7)

Other

Mojang has recognized this exploit as a bug to be fixed Mojira Report. But Paper should still patch this out asap.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

No source file or test is named. Reproduce the charge-timing case on Paper 1.21.8-60 using the linked recording and trace the crossbow charge handling; done means releasing just before the charge completes consistently triggers cooldown.

Written by the indexing model from the issue text.

Assessment

Tech stack
java
Domain
backend, game-dev
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Quiet
Clarity
Mostly clear
Newbie friendliness
45/100

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.