gpgtar in GnuPG before 2.5.19 can allow file overwrite via crafted data in an archive. When extracting an untrusted archive with –directory (aka -C) into an existing directory containing a pre-existing symlink, gpgtar can follow that symlink and create or overwrite a file outside the selected extraction directory. The write is limited by the extraction users filesystem permissions. An archive extracted into a fresh empty directory does not have this risk.
Weakness
The product, when opening a file or directory, does not sufficiently account for when the file is a symbolic link that resolves to a target outside of the intended control sphere. This could allow an attacker to cause the product to operate on unauthorized files.
Potential Mitigations
- Follow the principle of least privilege when assigning access rights to entities in a software system.
- Denying access to a file can prevent an attacker from replacing that file with a link to a sensitive file. Ensure good compartmentalization in the system to provide protected areas that can be trusted.