Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
dpkg 1.15.9, 1.16.x before 1.16.14, and 1.17.x before 1.17.9 expect the patch program to be compliant with a need for the "C-style encoded filenames" feature, but is supported in environments with noncompliant patch programs, which triggers an interaction error that allows remote attackers to conduct directory traversal attacks and modify files outside of the intended directories via a crafted source package. NOTE: this vulnerability exists because of reliance on unrealistic constraints on the behavior of an external program.
CWE-22 - Path Traversal
Path traversal (or directory traversal), is a vulnerability that allows malicious users to traverse the server's root directory, gaining access to arbitrary files and folders such as application code & data, back-end credentials, and sensitive operating system files. In the worst-case scenario, an attacker could potentially execute arbitrary files on the server, resulting in a denial of service attack. Such an exploit may severely impact the integrity, confidentiality, and availability of an application.