CVE-2021-47228
6.2 · MEDIUMIn the Linux kernel, the following vulnerability has been resolved: x86/ioremap: Map EFI-reserved memory as encrypted for SEV Some drivers require memory that is marked as EFI boot services data.
Overview
CVE-2021-47228 is a medium-severity vulnerability. It was published on May 21, 2024 and has a CVSS 3.1 base score of 6.2 (MEDIUM).
This vulnerability has a CVSS 3.1 base score of 6.2, rated MEDIUM. It requires local or adjacent network access to exploit. No authentication or special privileges are required for exploitation.
Technical description
In the Linux kernel, the following vulnerability has been resolved:
x86/ioremap: Map EFI-reserved memory as encrypted for SEV
Some drivers require memory that is marked as EFI boot services
data. In order for this memory to not be re-used by the kernel
after ExitBootServices(), efi_mem_reserve() is used to preserve it
by inserting a new EFI memory descriptor and marking it with the
EFI_MEMORY_RUNTIME attribute.
Under SEV, memory marked with the EFI_MEMORY_RUNTIME attribute needs to
be mapped encrypted by Linux, otherwise the kernel might crash at boot
like below:
EFI Variables Facility v0.08 2004-May-17
general protection fault, probably for non-canonical address 0x3597688770a868b2: 0000 [#1] SMP NOPTI
CPU: 13 PID: 1 Comm: swapper/0 Not tainted 5.12.4-2-default #1 openSUSE Tumbleweed
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
RIP: 0010:efi_mokvar_entry_next
[...]
Call Trace:
efi_mokvar_sysfs_init
? efi_mokvar_table_init
do_one_i
Remediation
Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
References
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Frequently asked questions
What is CVE-2021-47228?
CVE-2021-47228 is a medium-severity vulnerability. It was published on May 21, 2024 and has a CVSS 3.1 base score of 6.2 (MEDIUM).
How severe is CVE-2021-47228?
This vulnerability has a CVSS 3.1 base score of 6.2, rated MEDIUM. It requires local or adjacent network access to exploit. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2021-47228?
Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2021-47228?
CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-47228 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.
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