CVE-2019-16155: 
FortiClient vulnerability analysis and mitigation

A privilege escalation vulnerability (CVE-2019-16155) was discovered in FortiClient for Linux versions 6.2.1 and below. The vulnerability affects the system backup functionality and was later addressed in version 6.2.3 (Fortiguard PSIRT, NVD).

The vulnerability allows a user with low privileges to overwrite system files as root with arbitrary content through system backup file via specially crafted 'BackupConfig' type IPC client requests to the fctsched process. Additionally, in FortiClient for Linux 6.2.2 and below, low privilege users can write the system backup file under root privilege through the GUI, potentially leading to root system file overwrite. The vulnerability has been assigned a CVSS v3.1 base score of 7.1 (HIGH) with the vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H (NVD).

The vulnerability can lead to privilege escalation, allowing low-privileged users to gain root access and potentially overwrite critical system files. This could result in system compromise and unauthorized access to root-level functionality (NVD).

Fortinet has addressed this vulnerability in FortiClient for Linux version 6.2.3. Users are advised to upgrade to this version or later to mitigate the risk (Fortiguard PSIRT).