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CVE-2021-47255

7.1 · HIGH

In the Linux kernel, the following vulnerability has been resolved: kvm: LAPIC: Restore guard to prevent illegal APIC register access Per the SDM, "any access that touches bytes 4 through 15 of a…

Published May 21, 2024EPSS 0.24%

Overview

CVE-2021-47255 is a high-severity vulnerability. It was published on May 21, 2024 and has a CVSS 3.1 base score of 7.1 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.1, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical description

In the Linux kernel, the following vulnerability has been resolved:

kvm: LAPIC: Restore guard to prevent illegal APIC register access

Per the SDM, "any access that touches bytes 4 through 15 of an APIC

register may cause undefined behavior and must not be executed."

Worse, such an access in kvm_lapic_reg_read can result in a leak of

kernel stack contents. Prior to commit 01402cf81051 ("kvm: LAPIC:

write down valid APIC registers"), such an access was explicitly

disallowed. Restore the guard that was removed in that commit.

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

Refgit.kernel.org/stable/c/018685461a5b9a9a70e664ac77aef0d7415a3fd5Refgit.kernel.org/stable/c/218bf772bddd221489c38dde6ef8e917131161f6Refgit.kernel.org/stable/c/a2aff09807fbe4018c269d3773a629949058b210Refgit.kernel.org/stable/c/bf99ea52970caeb4583bdba1192c1f9b53b12c84Refgit.kernel.org/stable/c/018685461a5b9a9a70e664ac77aef0d7415a3fd5Refgit.kernel.org/stable/c/218bf772bddd221489c38dde6ef8e917131161f6Refgit.kernel.org/stable/c/a2aff09807fbe4018c269d3773a629949058b210Refgit.kernel.org/stable/c/bf99ea52970caeb4583bdba1192c1f9b53b12c84

How CyberStrike helps

Frequently asked questions

What is CVE-2021-47255?

CVE-2021-47255 is a high-severity vulnerability. It was published on May 21, 2024 and has a CVSS 3.1 base score of 7.1 (HIGH).

How severe is CVE-2021-47255?

This vulnerability has a CVSS 3.1 base score of 7.1, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2021-47255?

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-2021-47255?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-47255 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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