BuildKit is a toolkit for converting source code to build artifacts in an efficient, expressive and repeatable manner. Prior to version 0.28.1, insufficient validation of Git URL fragment subdir components may allow access to files outside the checked-out Git repository root. Possible access is limited to files on the same mounted filesystem. The issue has been fixed in version v0.28.1 The issue affects only builds that use Git URLs with a subpath component. As a workaround, avoid building Dockerfiles from untrusted sources or using the subdir component from an untrusted Git repository where the subdir component could point to a symlink.

BuildKit is a toolkit for converting source code to build artifacts in an efficient, expressive and repeatable manner. Prior to version 0.28.1, when using a custom BuildKit frontend, the frontend can craft an API message that causes files to be written outside of the BuildKit state directory for the execution context. The issue has been fixed in v0.28.1. The vulnerability requires using an untrusted BuildKit frontend set with `#syntax` or `--build-arg BUILDKIT_SYNTAX`. Using these options with a well-known frontend image like `docker/dockerfile` is not affected.