CVE-2021-3695 Memory corruption in grub2
A crafted PNG image triggers a heap out-of-bounds write in GRUB, potentially allowing arbitrary code execution and secure boot bypass.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2021-3695?
CVE-2021-3695 is a medium-severity memory corruption vulnerability in Fedoraproject Fedora, published on 6 Jul 2022. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
A crafted 16-bit grayscale PNG image may lead to a out-of-bounds write in the heap area. An attacker may take advantage of that to cause heap data corruption or eventually arbitrary code execution and circumvent secure boot protections. This issue has a high complexity to be exploited as an attacker needs to perform some triage over the heap layout to achieve signifcant results, also the values written into the memory are repeated three times in a row making difficult to produce valid payloads. This flaw affects grub2 versions prior grub-2.12.
Weakness: CWE-787
Which versions are affected by CVE-2021-3695?
It affects 14 products.
Products include Fedoraproject Fedora, Gnu Grub2, Netapp Ontap Select Deploy Administration Utility, Redhat Codeready Linux Builder, Redhat Developer Tools, Redhat Enterprise Linux and 8 more.
How do I fix CVE-2021-3695?
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-2021-3695 being exploited?
There is no known exploitation of CVE-2021-3695 in the wild and no public exploit code.
Other vulnerabilities in Fedoraproject Fedora
Sources
Also known as AZL-31034, AZL-34783, DEBIAN-CVE-2021-3695, GHSA-xjhh-w3rj-8mxm, UBUNTU-CVE-2021-3695.