fstream before 1.0.12 is vulnerable to Arbitrary File Overwrite. Extracting tarballs containing a hardlink to a file that already exists in the system, and a file that matches the hardlink, will overwrite the system's file with the contents of the extracted file. The fstream.DirWriter() function is vulnerable.
Exploitability
AV:NAC:LPR:NUI:NScope
S:UImpact
C:NI:HA:N7.5/CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N