--- title: 'USN-4992-1: GRUB 2 vulnerabilities | Ubuntu security notices' description: Ubuntu is an open source software operating system that runs from the desktop, to the cloud, to all your internet connected things. url: https://ubuntu.com/security/notices/USN-4992-1 --- 1. [Ubuntu Security Notices](https://ubuntu.com/security/notices) 2. USN-4992-1 --- # USN-4992-1: GRUB 2 vulnerabilities Publication date 18 June 2021 Overview Several security issues were fixed in GRUB 2. Releases [20.10](https://ubuntu.com/security/notices?release=groovy) [20.04 LTS](https://ubuntu.com/security/notices?release=focal) [18.04 LTS](https://ubuntu.com/security/notices?release=bionic) --- Open side navigation ## Packages * [grub2-signed](https://ubuntu.com/security/cves?package=grub2-signed) - GRand Unified Bootloader * [grub2-unsigned](https://ubuntu.com/security/cves?package=grub2-unsigned) - GRand Unified Bootloader ## Details Máté Kukri discovered that the acpi command in GRUB 2 allowed privileged users to load crafted ACPI tables when secure boot is enabled. An attacker could use this to bypass UEFI Secure Boot restrictions. ([CVE-2020-14372](https://ubuntu.com/security/CVE-2020-14372)) Chris Coulson discovered that the rmmod command in GRUB 2 contained a use- after-free vulnerability. A local attacker could use this to execute arbitrary code and bypass UEFI Secure Boot restrictions. ([CVE-2020-25632](https://ubuntu.com/security/CVE-2020-25632)) Chris Coulson discovered that a buffer overflow existed in the command line parser in GRUB 2. A local attacker could use this to execute arbitrary code and bypass UEFI Secure Boot restrictions. ([CVE-2020-27749](https://ubuntu.com/security/CVE-2020-27749)) It was discovered that the cutmem command in GRUB 2 did not honor secure boot locking. A local attacker could use this to execute arbitrary code and bypass UEFI Secure Boot... --- Show more ## Update instructions After a standard system update you need to reboot your computer to make all the necessary changes. [Learn more about how to get the fixes.](https://ubuntu.com/security/cves/about#security) The problem can be corrected by updating your system to the following package versions: | Ubuntu Release | Package Version | | --- | --- | | 20.10 groovy | [grub-efi-amd64-bin](https://launchpad.net/ubuntu/+source/grub2-unsigned) –  [2.04-1ubuntu44.2](https://launchpad.net/ubuntu/+source/grub2-unsigned/2.04-1ubuntu44.2) | | | | [grub-efi-amd64-signed](https://launchpad.net/ubuntu/+source/grub2-signed) –  [1.167.2+2.04-1ubuntu44.2](https://launchpad.net/ubuntu/+source/grub2-signed/1.167.2) | | | | [grub-efi-arm64-bin](https://launchpad.net/ubuntu/+source/grub2-unsigned) –  [2.04-1ubuntu44.2](https://launchpad.net/ubuntu/+source/grub2-unsigned/2.04-1ubuntu44.2) | | | | [grub-efi-arm64-signed](https://launchpad.net/ubuntu/+source/grub2-signed) –  [1.167.2+2.04-1ubuntu44.2](https://launchpad.net/ubuntu/+source/grub2-signed/1.167.2) | | | | 20.04 LTS focal | [grub-efi-amd64-bin](https://launchpad.net/ubuntu/+source/grub2-unsigned) –  [2.04-1ubuntu44.2](https://launchpad.net/ubuntu/+source/grub2-unsigned/2.04-1ubuntu44.2) | | | | [grub-efi-amd64-signed](https://launchpad.net/ubuntu/+source/grub2-signed) –  [1.167.2+2.04-1ubuntu44.2](https://launchpad.net/ubuntu/+source/grub2-signed/1.167.2) | | | | [grub-efi-arm64-bin](https://launchpad.net/ubuntu/+source/grub2-unsigned) –  [2.04-1ubuntu44.2](https://launchpad.net/ubuntu/+source/grub2-unsigned/2.04-1ubuntu44.2) | | | | [grub-efi-arm64-signed](https://launchpad.net/ubuntu/+source/grub2-signed) –  [1.167.2+2.04-1ubuntu44.2](https://launchpad.net/ubuntu/+source/grub2-signed/1.167.2) | | | | 18.04 LTS bionic | [grub-efi-amd64-bin](https://launchpad.net/ubuntu/+source/grub2-unsigned) –  [2.04-1ubuntu44.1.2](https://launchpad.net/ubuntu/+source/grub2-unsigned/2.04-1ubuntu44.1.2) | | | | [grub-efi-amd64-signed](https://launchpad.net/ubuntu/+source/grub2-signed) –  [1.167~18.04.5+2.04-1ubuntu44.1.2](https://launchpad.net/ubuntu/+source/grub2-signed/1.167~18.04.5) | | | | [grub-efi-arm64-bin](https://launchpad.net/ubuntu/+source/grub2-unsigned) –  [2.04-1ubuntu44.1.2](https://launchpad.net/ubuntu/+source/grub2-unsigned/2.04-1ubuntu44.1.2) | | | | [grub-efi-arm64-signed](https://launchpad.net/ubuntu/+source/grub2-signed) –  [1.167~18.04.5+2.04-1ubuntu44.1.2](https://launchpad.net/ubuntu/+source/grub2-signed/1.167~18.04.5) | | | --- ### Reduce your security exposure Ubuntu Pro provides ten-year security coverage to 25,000+ packages in Main and Universe repositories, and it is free for up to five machines. [Get Ubuntu Pro](https://ubuntu.com/pro) ## References * * [CVE-2021-20233](https://ubuntu.com/security/CVE-2021-20233) * [CVE-2021-20225](https://ubuntu.com/security/CVE-2021-20225) * [CVE-2020-27779](https://ubuntu.com/security/CVE-2020-27779) * [CVE-2020-27749](https://ubuntu.com/security/CVE-2020-27749) * [CVE-2020-25632](https://ubuntu.com/security/CVE-2020-25632) * [CVE-2020-14372](https://ubuntu.com/security/CVE-2020-14372)