BuildKit Git URL subdir component can cause access to restricted files in github.com/moby/buildkit

Open Source Vulnerabilities GHSA-4vrq-3vrq-g6gg

### Impact Insufficient validation of Git URL fragment subdir components (`<url>#<ref>:<subdir>`, [docs](https://docs.docker.com/build/concepts/context/#url-fragments)) may allow access to files outside the checked-out Git repository root. Possible access is limited to files on the same mounted filesystem. ### Patches The issue has been fixed in version v0.28.1 ### Workarounds The issue affects only builds that use Git URLs with a subpath component. 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.

Open Source Vulnerabilities GO-2026-4859

BuildKit Git URL subdir component can cause access to restricted files in github.com/moby/buildkit

Open Source Vulnerabilities CVE-2026-33748

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.