AIKIDO-2026-334127

TL;DR

kubectl cp copies files out of a container by running tar inside the container and unpacking the resulting archive on the local machine. On Windows clients, the isRelative path check normalizes forward slashes but not backslashes, so a crafted tar stream from a container with untrusted contents can include a path that the check accepts as relative even though it escapes the destination directory, which lets the archive create or overwrite files at arbitrary paths on the local Windows machine, limited only by the local user's filesystem permissions. The fix normalizes backslashes to forward slashes before computing and validating the relative path.