GHSA-x86f-5xw2-fm2r

## Summary When a user uploads a compressed archive into a container, a malicious image can execute arbitrary code with daemon (host root) privileges. ## Details When handling `PUT /containers/{id}/archive` requests with compressed archives, the daemon decompresses them using external system binaries. Due to incorrect ordering of operations, these binaries are resolved from the container's filesystem rather than the host's. A container image that includes a trojanized decompression binary can achieve code execution as the daemon process whenever a compressed archive is uploaded to that container. The executed binary runs with the daemon's full privileges, including host root UID and unrestricted capabilities. ## Impact Arbitrary code execution as host root, crossing the container-to-host trust boundary. ### Conditions for exploitation - A user must run a container from a malicious image that contains a trojanized decompression binary. - The user must then upload a compressed archive (xz or gzip) into that container, either by piping a compressed archive via `docker cp -` or by calling the `PUT /containers/{id}/archive` API directly with compressed content. ### Not affected Standard `docker cp` usage is **not** affected, because the CLI sends uncompressed tar by default: ``` docker cp ./file.txt mycontainer:/file.txt ``` This can only be exploited when explicitly passing a xz or gzip-compressed archive to `docker cp` or the `PUT /containers/{id}/archive` API, for example: ``` cat archive.tar.xz | docker cp - mycontainer:/dir ``` Decompression formats using pure Go implementations (bzip2, zstd, and gzip when the container image does not contain an `unpigz` binary) are also not affected. ## Workarounds - Only run containers from trusted images. - Use authorization plugins to limit access to the `PUT /containers/{id}/archive` endpoint. - Avoid piping compressed archives into containers created from untrusted images.