SourceTree for Windows Security Advisory 24th March 2021

Still need help?

The Atlassian Community is here for you.

Ask the community

SourceTree for Windows - Remote Code Injection using Git LFS - CVE-2020-27955 & CVE-2021-21237


CVE-2020-27955 & CVE-2021-21237 - Remote Code Injection using Git LFS

Advisory Release Date

24 March 2021, 10:00 AM PDT (Pacific Time, -7 hours)


SourceTree for Windows

Affected Versions

Version 3.4.2 and earlier

Fixed Versions

Version 3.4.3 and later




Summary of Vulnerability

This advisory discloses a critical severity security vulnerability which was introduced through the git-lfs library and discovered in version 3.3.9 of SourceTree for Windows. Both CVE-2020-27955 & CVE-2021-21237 refer to the same underlying vulnerability, Remote Code Injection using Git LFS. Versions of SourceTree for Windows starting with 0.9.4 before 3.4.3 (the fixed version for CVE-2020-27955 and CVE-2021-21237) are affected by this vulnerability.

Customers who have upgraded to version 3.4.3 are not affected.

Customers who have installed versions <= 3.4.2 (the fixed version for versions < 3.4.3)

Please upgrade your installations immediately to fix this vulnerability.

Remote Code Injection using Git LFS - CVE-2020-27955 & CVE-2021-21237


Atlassian rates the severity level of this vulnerability as critical, according to the scale published in our Atlassian severity levels. The scale allows us to rank the severity as critical, high, moderate or low.

This is our assessment and you should evaluate its applicability to your own IT environment.


Vulnerability occurs when a user clones a malicious repository and tries to enable Git LFS to the repository

  1. Clone the repository

  2. Go to the Repository Tab -> Git LFS -> Start Repo

Loading a malicious repository will allow an attacker to execute arbitrary commands on the system.

All versions of SourceTree for Windows up to and including 3.4.2 are affected by this vulnerability.

This issue can be tracked here:

SRCTREEWIN-13410 - RCE via git-lfs in Sourcetree for Windows - CVE-2020-27955 CLOSED

SRCTREEWIN-13480 - RCE via git-lfs in Sourcetree for Windows - CVE-2021-21237 CLOSED

Vulnerability References


We have taken the following steps to address this issue:

  1. Released version 3.4.3 that contains a fix for this issue.

What You Need to Do

Atlassian recommends that you upgrade to the latest version. For a full description of the latest version of SourceTree for Windows, see the release notes. Download the latest version of the standard installer or the enterprise installer.

Upgrade to version 3.4.3 or higher.


  • Update git and git-lfs on your system to the latest versions and use them in your existing Sourcetree.


If you did not receive an email for this advisory and you wish to receive such emails in the future go to and subscribe to Alerts emails.
If you have questions or concerns regarding this advisory, please raise a support request at


Security Bug fix Policy

As per our new policy critical security bug fixes will be back ported in accordance with  We will release new maintenance releases for the versions covered by the policy instead of binary patches.

Binary patches are no longer released. 

Severity Levels for security issues

Atlassian security advisories include a severity level and a CVE identifier. This severity level is based on our self-calculated CVSS score for each specific vulnerability. CVSS is an industry standard vulnerability metric. You can also learn more about CVSS at

End of Life Policy

 Our end of life policy varies for different products. Please refer to our EOL Policy for details. 

Last modified on Apr 7, 2021

Was this helpful?

Provide feedback about this article
Powered by Confluence and Scroll Viewport.