SourceTree for Windows Security Advisory 24th March 2021
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
Version 3.4.2 and earlier
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
Clone the repository
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:
CVE-2020-27955 advisory from Github: https://github.com/git-lfs/git-lfs/security/advisories/GHSA-4g4p-42wc-9f3m
CVE-2021-21237 advisory from Github: https://github.com/git-lfs/git-lfs/security/advisories/GHSA-cx3w-xqmc-84g5
Original advisory by Dawid Golunski: https://legalhackers.com/advisories/Git-LFS-RCE-Exploit-CVE-2020-27955.html
We have taken the following steps to address this issue:
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 https://my.atlassian.com/email and subscribe to Alerts emails.
If you have questions or concerns regarding this advisory, please raise a support request at https://support.atlassian.com/.
As per our new policy critical security bug fixes will be back ported in accordance with https://www.atlassian.com/trust/security/bug-fix-policy. We will release new maintenance releases for the versions covered by the policy instead of binary patches.
Binary patches are no longer released.
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 FIRST.org.
Our end of life policy varies for different products. Please refer to our EOL Policy for details.