Ghost is an open source content management system. Versions prior to 5.59.1 are subject to a vulnerability which allows authenticated users to upload files that are symlinks. This can be exploited to perform an arbitrary file read of any file on the host operating system. Site administrators can check for exploitation of this issue by looking for unknown symlinks within Ghost's `content/` folder. Version 5.59.1 contains a fix for this issue. All users are advised to upgrade. There are no known workarounds for this vulnerability.
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.
The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.