Improper Access Control on Deploy-Key

HackerOne report #962231 by ledz1996 on 2020-08-19:

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Summary

Similar Issue to #957459, This time on Deploy-Key

Security Issue https://gitlab.com/gitlab-org/security/gitlab/-/issues/227

Steps to reproduce

1. As User A, for me root, Create a project. Set to Public with Repository only to Member
2. As User B, create any project then create a Deploy-Key for that project
   Generate a SSH-Key to get the Public key

ssh-keygen -t rsa -b 2048 -C "email@example.com"  

Copy the content of id_rsa.pub for the Deploy-Key

git clone git@gitlab.example.vm:private-user/private-repo.git  

I prepare a video for this: Screen_Recording_2020-08-19_at_18.37.42.mov

Results of GitLab environment info

System information  
System:  
Proxy:		no  
Current User:	git  
Using RVM:	no  
Ruby Version:	2.6.6p146  
Gem Version:	2.7.10  
Bundler Version:1.17.3  
Rake Version:	12.3.3  
Redis Version:	5.0.9  
Git Version:	2.27.0  
Sidekiq Version:5.2.9  
Go Version:	unknown

GitLab information  
Version:	13.2.6-ee  
Revision:	e231b6a0b09  
Directory:	/opt/gitlab/embedded/service/gitlab-rails  
DB Adapter:	PostgreSQL  
DB Version:	11.7  
URL:		http://gitlab.example.vm  
HTTP Clone URL:	http://gitlab.example.vm/some-group/some-project.git  
SSH Clone URL:	git@gitlab.example.vm:some-group/some-project.git  
Elasticsearch:	no  
Geo:		no  
Using LDAP:	no  
Using Omniauth:	yes  
Omniauth Providers:

GitLab Shell  
Version:	13.3.0  
Repository storage paths:  
- default: 	/var/opt/gitlab/git-data/repositories  
GitLab Shell path:		/opt/gitlab/embedded/service/gitlab-shell  
Git:		/opt/gitlab/embedded/bin/git  

Impact

Read private files in project

Attachments

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• Screen_Recording_2020-08-19_at_18.37.42.mov

How To Reproduce

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