Improper access control allows the attacker to comment on an internal commit after he's no longer an admin

HackerOne report #635512 by hx01 on 2019-07-04:

Description:

the attacker (previously maintainer) is able to comment in internal commits by replying to the notification email which were received before :
reply.png

Steps to reproduce Setup:

  1. victim@domain.tld (maintainer)
  2. attacker@doamin.tld(maintainer)

PoC :

  1. the analyst should comment on their commit with victim@domain.tld --> attacker@doamin.tld will receive the notification.
  2. the analyst should remove the attacker@doamin.tld role after that
  3. the analyst should reply to the notification email received.:
    reply.png
  4. bingo! it will be posted to the commit :
    post.png

Impact

this could be exploited to comment on the commits by the attacker who was accidentally added to the project or was removed .

Attachments

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Edited by Heinrich Lee Yu