Maliciously crafted Git server replies can lead to path traversal and RCE on go-git clients

Impact

A path traversal vulnerability was discovered in go-git versions prior to v5.11. This vulnerability allows an attacker to create and amend files across the filesystem. In the worse case scenario, remote code execution could be achieved.

Applications are only affected if they are using the ChrootOS, which is the default when using “Plain” versions of Open and Clone funcs (e.g. PlainClone). Applications using BoundOS or in-memory filesystems are not affected by this issue.
This is a go-git implementation issue and does not affect the upstream git cli.

Patches

Users running versions of go-git from v4 and above are recommended to upgrade to v5.11 in order to mitigate this vulnerability.

Workarounds

In cases where a bump to the latest version of go-git is not possible in a timely manner, we recommend limiting its use to only trust-worthy Git servers.

Credit

Thanks to Ionut Lalu for responsibly disclosing this vulnerability to us.