CVE-2021-46977

KVM: VMX: Disable preemption when probing user return MSRs

MEDIUM
5.5
CVSS Score
Published: February 28, 2024 at 08:13 AM UTC
Updated: August 5, 2026 at 09:24 AM UTC
1 product affected across 1 vendorLinux Kernel

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Severity
MEDIUM5.5
Exploit prediction
EPSS 0.2%
SSVC
No known exploit

Description

In the Linux kernel, the following vulnerability has been resolved: KVM: VMX: Disable preemption when probing user return MSRs Disable preemption when probing a user return MSR via RDSMR/WRMSR. If the MSR holds a different value per logical CPU, the WRMSR could corrupt the host's value if KVM is preempted between the RDMSR and WRMSR, and then rescheduled on a different CPU. Opportunistically land the helper in common x86, SVM will use the helper in a future commit.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

5.11 ≤ v < 5.11.225.12 ≤ v < 5.12.55.5 ≤ v < 5.10.385.5 ≤ v < 5.11.225.5 ≤ v < 5.12.55.5 ≤ v < 5.134be5341026246870818e28b53202b001426a5aec5.13 rc1
Vendor states this is fixed in 31f29749ee970c251b3a7e5b914108425940d089 (fixed)
Vendor states this is fixed in 5104d7ffcf24749939bea7fdb5378d186473f890 (fixed)
Vendor states this is fixed in 5adcdeb57007ccf8ab7ac20bf787ffb6fafb1a94 (fixed)
Vendor states this is fixed in e3ea1895df719c4ef87862501bb10d95f4177bed (fixed)
Vendor states this is fixed in 5.10.38 (unaffected)
Vendor states this is fixed in 5.11.22 (unaffected)
Vendor states this is fixed in 5.12.5 (unaffected)
Vendor states this is fixed in 5.13 (unaffected)
Vendor states this is fixed in 5.5 (unaffected)

References (4)

Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/31f29749ee970c251b3a7e5b914108425940d089
Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/5104d7ffcf24749939bea7fdb5378d186473f890
Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/5adcdeb57007ccf8ab7ac20bf787ffb6fafb1a94
Patch
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/e3ea1895df719c4ef87862501bb10d95f4177bed

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
LOCAL
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
NVD-CWE-noinfo

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