CVE-2026-124745: Busybox: tar deferred hardlink target resolved through a deferred symlink escapes the extraction directory
A flaw was found in BusyBox. When extracting an archive, the tar utility improperly resolves deferred hardlink targets across symbolic links pointing outside the intended extraction directory. An attacker could provide a specially crafted archive that links to sensitive files outside the extraction tree, allowing subsequent extraction operations to overwrite arbitrary files on the system.
Other sources
A flaw was found in BusyBox's tar. The target of a deferred hardlink is resolved through deferred symlinks in its directory components: a symlink entry pointing outside the extraction directory, followed by a hardlink entry whose target passes through that symlink, makes the created hardlink refer to a file outside the extraction directory. A crafted archive can exploit this to pull an arbitrary outside file into the extraction tree as a hardlink; a second archive extracted into the same directory with an overwriting extractor could then replace the outside file's content.
— Red Hat