Bootloader Vulnerability Affects Nearly All Linux Distributions
The developers of shim have released a version to fix numerous security flaws, including one that could enable remote control execution of malicious code under certain circumstances.
CVE-2023-40547 has a CVSS score of 8.3, which means it's labeled as High. Originally, the vulnerability was given a score of 9.8 (which placed it in the Critical category) but that has since changed.
This vulnerability was discovered in shim, which is a small application that loads prior to the main operating system bootloader (such as Grub) on UEFI-based systems.
The flaw could allow an attack to create a specific HTTP request that could enable a controlled out-of-bounds write primitive, which could lead to complete system compromise.
According to Bill Demirkapi (from the Microsoft Security Response Center), the bug exists in every Linux bootloader signed in the past decade.
The official description of the issue explains, "When retrieving files via HTTP or related protocols, shim attempts to allocate a buffer to store the received data. Unfortunately, this means getting the size from an HTTP header, which can be manipulated to specify a size that's smaller than the received data. In this case, the code accidentally uses the header for the allocation but the protocol metadata to copy it from the rx buffer, resulting in an out-of-bounds write."
Fortunately, all major distributions have released patches for the vulnerability, so users only need to run an update on their systems to avoid being exposed to the issue.
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.
News
-
Plasma 6.3 Now Available
Plasma desktop v6.3 has a couple of pretty nifty tricks up its sleeve.
-
LibreOffice 25.2 Has Arrived
If you've been hoping for a release that offers more UI customizations, you're in for a treat.
-
TuxCare Has a Big AlmaLinux 9 Announcement in Store
TuxCare announced it has successfully completed a Security Technical Implementation Guide for AlmaLinux OS 9.
-
First Release Candidate for Linux Kernel 6.14 Now Available
Linus Torvalds has officially released the first release candidate for kernel 6.14 and it includes over 500,000 lines of modified code, making for a small release.
-
System76 Refreshes Meerkat Mini PC
If you're looking for a small form factor PC powered by Linux, System76 has exactly what you need in the Meerkat mini PC.
-
Gnome 48 Alpha Ready for Testing
The latest Gnome desktop alpha is now available with plenty of new features and improvements.
-
Wine 10 Includes Plenty to Excite Users
With its latest release, Wine has the usual crop of bug fixes and improvements, along with some exciting new features.
-
Linux Kernel 6.13 Offers Improvements for AMD/Apple Users
The latest Linux kernel is now available, and it includes plenty of improvements, especially for those who use AMD or Apple-based systems.
-
Gnome 48 Debuts New Audio Player
To date, the audio player found within the Gnome desktop has been meh at best, but with the upcoming release that all changes.
-
Plasma 6.3 Ready for Public Beta Testing
Plasma 6.3 will ship with KDE Gear 24.12.1 and KDE Frameworks 6.10, along with some new and exciting features.