Dropbear before 2017.75 might allow local users to read certain files as root, if the file has the authorizedkeys file format with a command= option. This occurs because ~/.ssh/authorizedkeys is read with root privileges and symlinks are followed.
{ "availability": "No subscription required", "ubuntu_priority": "medium", "binaries": [ { "binary_version": "2017.75-3build1", "binary_name": "dropbear" }, { "binary_version": "2017.75-3build1", "binary_name": "dropbear-bin" }, { "binary_version": "2017.75-3build1", "binary_name": "dropbear-bin-dbgsym" }, { "binary_version": "2017.75-3build1", "binary_name": "dropbear-initramfs" }, { "binary_version": "2017.75-3build1", "binary_name": "dropbear-run" } ] }