usd-2019-0018 | Bitbucket/v5.10.1

Advisory ID: usd-2019-0018
CVE number: N/A
Affected Version: v5.10.1
Vulnerability Type: User Enumeration
Impact: Low
First Pubslished: 2019-07-31
Last Update: 2019-05-27


Security Risk: Low
Vendor URL:
Vendor Status: Not fixed
Advisory Status: Published


Access control, sometimes called authorization, is how a web application grants access to content and functions to some users and not others. These checks are performed after authentication and govern what ‘authorized’ users are allowed to do. Access control sounds like a simple task. However, this is insidiously difficult to implement correctly. A web application’s access control model is closely tied to the content and functions that the site provides. In addition, the users may fall into a number of groups or roles with different abilities or privileges.


Unprivileged users are able to enumerate valid usernames. Hereto, an user sends a request to „/admin/permissions/users“ with following request

GET-Parameter „?permission=LICENSED_USER&name=“.

If the username exists, the server responds with an error message that the user has unsufficient rights for this process.
If the username does not exists, the server responds with a message that the user does not exists.


Even if the user doesn’t exists, the server should respond with an error message which points out that the user doesn’t have sufficient rights to execute the process.


  • 2019-03-28 Vulnerability securily submitted to
  • 2019-04-11 Second contact attempt via contact formular
  • 2019-05-23 Atlassian Security Team agreed with the publishment of the advisory


This security vulnerabilities were found by Tobias Neitzel and Julian Frey of usd AG.


In order to protect businesses against hackers and criminals, we always have to keep our skills and knowledge up to date. Thus, security research is just as important for our work as is building up a security community to promote the exchange of knowledge. After all, more security can only be achieved if many individuals take on the task.

Our CST Academy and our usd HeroLab are essential parts of our security mission. We share the knowledge we gain in our practical work and our research through training courses and publications. In this context, the usd HeroLab publishes a series of papers
on new vulnerabilities and current security issues.

Always for the sake of our mission: „more security.“

to usd AG

In accordance with usd AG’s Responsible Disclosure Policy, all vendors have been notified of the existence of these vulnerabilities.


The information provided in this security advisory is provided „as is“ and without warranty of any kind. Details of this security advisory may be updated in order to provide as accurate information as possible.