CVE-2021-47255

CVE-2021-47255 is a high-severity vulnerability in Linux Linux Kernel with a CVSS 3.x base score of 7.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

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.

Frequently asked questions

What is CVE-2021-47255?
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.
How severe is CVE-2021-47255?
CVE-2021-47255 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability high.
Is CVE-2021-47255 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-47255?
CVE-2021-47255 primarily affects Linux Linux Kernel. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-47255?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2021-47255 have an EU (EUVD) identifier?
Yes. CVE-2021-47255 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-33903.
When was CVE-2021-47255 published?
CVE-2021-47255 was published on 2024-05-21 and last updated on 2026-06-17.

References

Affected products (7)

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