PT-2024-11112 · Linux · Linux Kernel

Tom Lendacky · Published 2021-04-19 · Updated 2024-12-09 · CVE-2021-47008

Positive Technologies (AI Summary)

CVSS v3.1

5.5

Medium

Base vector

AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Name of the Vulnerable Software and Affected Versions Linux kernel (affected versions not specified)

Description The issue is related to the KVM: SVM component of the Linux kernel. Access to the GHCB (Guest-to-Host Communication Buffer) is mainly in the VMGEXIT path and it is known that the GHCB will be mapped. However, 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. If a SIPI is performed without a corresponding AP Reset Hold, then the GHCB might not be mapped, 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. A safe guard has been added in this path to be certain a NULL pointer dereference is not encountered.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.

NULL Pointer Dereference

Weakness Enumeration

CWE-476

Related Identifiers

BDU:2025-06538

CVE-2021-47008

Affected Products

Linux Kernel

References · 16

• https://osv.dev/vulnerability/UBUNTU-CVE-2021-47008 · Vendor Advisory
• https://cve.org/CVERecord?id=CVE-2021-47008 · Security Note
• https://ubuntu.com/security/CVE-2021-47008 · Vendor Advisory
• https://git.kernel.org/stable/c/a3ba26ecfb569f4aa3f867e80c02aa65f20aadad · Patch
• https://git.kernel.org/stable/c/fd722a57fe0b80133dacae4e1c852ee4212f9b2e · Patch
• https://nvd.nist.gov/vuln/detail/CVE-2021-47008 · Security Note
• https://git.kernel.org/stable/c/fb9e14f4f8217a0980f8da2c8ff70dee058cbe47 · Patch
• https://osv.dev/vulnerability/CVE-2021-47008 · Vendor Advisory
• https://bdu.fstec.ru/vul/2025-06538 · Security Note
• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-47008 · Note
• https://twitter.com/CVEnew/status/1762754418741833799 · Twitter Post
• https://lore.kernel.org/linux-cve-announce/2024022830-CVE-2021-47008-3dc3@gregkh/T/#u · Note
• https://kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.12.5 · Note
• https://lore.kernel.org/linux-cve-announce/2024022830-CVE-2021-47008-3dc3@gregkh · Note
• https://kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.11.22 · Note