Linux administrators are urged to watch for and install patches to fix two major vulnerabilities in the operating system.
Both discovered by researchers at Qualys, one is a stack exhaustion denial-of-service vulnerability in systemd, described as a near-ubiquitous utility available on major Linux operating systems and the second is a flaw in the Linux kernel filesystem layer that could allow an unprivileged user to gain root privileges.
Systemd vulnerability
“Any unprivileged user can exploit this vulnerability to crash systemd and hence the entire operating system (a kernel panic),” the company said in a blog. Systemd is a software suite that’s included in most Linux-based OSes which provides an array of system components for Linux operating systems, including a system and service manager that runs as PID 1 and starts the rest of the system.
The vulnerability dates back to April, 2015, when it was introduced to a version added to the operating system.
Red Hat and Ubuntu have issued patches for their Linux distributions.
Filesystem flaw
Separately, Linux administrators have been warned to watch for patches to fix a vulnerability in the Linux kernel’s filesystem layer that could allow any unprivileged user to gain root privileges on a vulnerable host. It is said to affect most Linux operating systems.
Under certain circumstances if an unprivileged local attacker creates, mounts, and deletes a deep directory structure whose total path length exceeds 1GB, they can obtain full root privileges. Qualys has shown that this works on default installations of Ubuntu 20.04, Ubuntu 20.10, Ubuntu 21.04, Debian 11, and Fedora 34 Workstation.
Red Hat released a patch on July 13th.
Given the breadth of the attack surfaces for both of these vulnerabilities, Qualys recommends users apply patches for them immediately.