CVE-2021-47008
MediumIn the Linux kernel, the following vulnerability has been resolved: KVM: SVM: Make sure GHCB is mapped before updating Access to the GHCB is mainly in the VMGEXIT path and it is known that the GHCB will be mapped. But there are two paths where it is possible the GHCB might not be mapped. The sev_vcpu_deliver_sipi_vector() routine will update the GHCB to inform the caller of the AP Reset Hold NAE event that a SIPI has been delivered. However, if a SIPI is performed without a corresponding AP Reset Hold, then the GHCB might not be mapped (depending on the previous VMEXIT), which will result in a NULL pointer dereference. The svm_complete_emulated_msr() routine will update the GHCB to inform the caller of a RDMSR/WRMSR operation about any errors. While it is likely that the GHCB will be mapped in this situation, add a safe guard in this path to be certain a NULL pointer dereference is not encountered.
CVSS 3.1 score
5.5
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness type
CWE-476CVE-2021-47008 is a NULL Pointer Dereference vulnerability
What is NULL Pointer Dereference?
The product dereferences a pointer that it expects to be valid but is NULL, typically causing a crash. Learn more on MITRE CWE
References
The following references provide additional information about CVE-2021-47008 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.
-
PatchKernel patch commithttps://git.kernel.org/stable/c/a3ba26ecfb569f4aa3f867e80c02aa65f20aadad
-
PatchKernel patch commithttps://git.kernel.org/stable/c/fb9e14f4f8217a0980f8da2c8ff70dee058cbe47
-
PatchKernel patch commithttps://git.kernel.org/stable/c/fd722a57fe0b80133dacae4e1c852ee4212f9b2e
Frequently asked questions
-
What is CVE-2021-47008?
CVE-2021-47008 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 , classified as a NULL Pointer Dereference flaw (CWE-476) . CVE-2021-47008 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
-
What is the CVSS score for CVE-2021-47008?
CVE-2021-47008 has a CVSS score of 5.5 out of 10, rated Medium severity (CVSS 3.1). The vector string is
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H. -
Is there a patch available for CVE-2021-47008?
No patch is currently available for CVE-2021-47008. Monitor the NIST NVD and your Linux distribution's security advisories for updates.
-
Is CVE-2021-47008 actively exploited?
No — CVE-2021-47008 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.
-
What is NULL Pointer Dereference (CWE-476)?
The product dereferences a pointer that it expects to be valid but is NULL, typically causing a crash. View CWE-476 on MITRE CWE →