KVM: SEV: Use READ_ONCE() when reading entries/indices from PSC buffer

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-63937
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-19 16:17:12 UTC
Updated2026-07-20 15:16:57 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: KVM: SEV: Use READ_ONCE() when reading entries/indices from PSC buffer Use READ_ONCE() when reading entries/indices from the guest-accessible Page State Change buffer to defend against TOCTOU bugs. Don't bother with READ_ONCE()/WRITE_ONCE() for cases where KVM is writing (and not consuming the result!), as the guest isn't supposed to touch the buffer while it's being processed. I.e. using READ_ONCE() is all about protecting against misbehaving guests.

Risk And Classification

Primary CVSS: v3.1 8.8 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

EPSS: 0.002000000 probability, percentile 0.100200000 (date 2026-07-20)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary8.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
3.1CNADECLARED8.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 9b54e248d2644be71cb394eb85f31ad99e023a05 bd232801ef1d1fd985d2d4ca3cd1d888303ca86f git Not specified
CNA Linux Linux affected 9b54e248d2644be71cb394eb85f31ad99e023a05 b1dfaa6f7a957726a6800135be3659fbe4bbf2a4 git Not specified
CNA Linux Linux affected 9b54e248d2644be71cb394eb85f31ad99e023a05 edbbe88f83b524434974e84808d3093199d67c24 git Not specified
CNA Linux Linux affected 9b54e248d2644be71cb394eb85f31ad99e023a05 c8cc238093ca6c99267032f6cfe78f59389f3157 git Not specified
CNA Linux Linux affected 6.11 Not specified
CNA Linux Linux unaffected 6.11 semver Not specified
CNA Linux Linux unaffected 6.12.93 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.35 6.18.* semver Not specified
CNA Linux Linux unaffected 7.0.12 7.0.* semver Not specified
CNA Linux Linux unaffected 7.1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/c8cc238093ca6c99267032f6cfe78f59389f3157 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b1dfaa6f7a957726a6800135be3659fbe4bbf2a4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/bd232801ef1d1fd985d2d4ca3cd1d888303ca86f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/edbbe88f83b524434974e84808d3093199d67c24 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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