Git source checkout from a bundle file could lead to command injection

Impact

BuildKit custom frontends or clients using the raw low-level API can set
git.checkoutbundle=true when checking out Git sources. If the Git source is
malicious, this could lead to a crafted command invocation on the host.

Patches

The issue has been fixed in v0.31.2+.

Workarounds

The issue requires using a custom frontend together with a malicious Git source. Current Dockerfile builds are not affected.

References

Credits

This issue was reported by Zhibin Hu and Lei Wang of HuaweiCloud