CVE-2020-15706 Use after free in grub2 in Ubuntu

What is CVE-2020-15706?

CVE-2020-15706 is a medium-severity use after free vulnerability in Canonical Ubuntu Linux, published on 29 Jul 2020. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

GRUB2 contains a race condition in grub_script_function_create() leading to a use-after-free vulnerability which can be triggered by redefining a function whilst the same function is already executing, leading to arbitrary code execution and secure boot restriction bypass. This issue affects GRUB2 version 2.04 and prior versions.

Weakness: CWE-416, CWE-362

Which versions are affected by CVE-2020-15706?

It affects 14 products.

Products include Canonical Ubuntu Linux, Debian Debian Linux, Gnu Grub2, Microsoft Windows 10, Microsoft Windows 8.1, Microsoft Windows Rt 8.1 and 8 more.

How do I fix CVE-2020-15706?

Apply the vendor's patch.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2020-15706 being exploited?

There is no known exploitation of CVE-2020-15706 in the wild and no public exploit code.

Other vulnerabilities in Canonical Ubuntu Linux

• CVE-2020-11651 SaltStack Salt Authentication Bypass Exploited Critical 9.8
• CVE-2020-7247 OpenSMTPD Remote Code Execution Exploited Critical 9.8
• CVE-2019-16928 Exim Out-of-bounds Write Exploited Critical 9.8
• CVE-2018-6789 Exim Buffer Overflow Exploited Critical 9.8
• CVE-2015-2590 Oracle Java SE and Java SE Embedded Remote Code Execution Exploited Critical 9.8

All Canonical Ubuntu Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as ALPINE-CVE-2020-15706, DEBIAN-CVE-2020-15706, GHSA-gmqm-wgp3-r69q, UBUNTU-CVE-2020-15706.