CVE-2020-27749 Memory corruption in grub2
Attacker can overflow stack buffer in GRUB2 to execute code and bypass Secure Boot, compromising system integrity and availability.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2020-27749?
CVE-2020-27749 is a medium-severity memory corruption vulnerability in Fedoraproject Fedora, published on 3 Mar 2021. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
A flaw was found in grub2 in versions prior to 2.06. Variable names present are expanded in the supplied command line into their corresponding variable contents, using a 1kB stack buffer for temporary storage, without sufficient bounds checking. If the function is called with a command line that references a variable with a sufficiently large payload, it is possible to overflow the stack buffer, corrupt the stack frame and control execution which could also circumvent Secure Boot protections. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.
Which versions are affected by CVE-2020-27749?
It affects 8 products.
Products include Fedoraproject Fedora, Gnu Grub2, Netapp Ontap Select Deploy Administration Utility, Redhat Enterprise Linux, Redhat Enterprise Linux Server Aus, Redhat Enterprise Linux Server Eus and 2 more.
How do I fix CVE-2020-27749?
Upgrade to a fixed version.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2020-27749 being exploited?
There is no known exploitation of CVE-2020-27749 in the wild and no public exploit code.
Other vulnerabilities in Fedoraproject Fedora
Sources
Also known as ALPINE-CVE-2020-27749, AZL-6463, DEBIAN-CVE-2020-27749, GHSA-258p-xh3c-g68w, UBUNTU-CVE-2020-27749.