qbee transport is a remote access transport protocol implementation. Prior to 1.26.25, the extractTar routine uses strictly lexical path validation that does not account for on-disk symlinks created earlier in the extraction process. A crafted tar archive can use a symlink chain to write or overwrite files one directory level above the intended extraction path. When qbee-agent performs the extraction with root privileges, this permits a root-privileged file write outside the intended destination. This issue is fixed in version 1.26.25.