Riskcovery

CVE-2026-63937

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

State
Published
Severity
8.8 High
Published
Jul 19, 2026
Updated
Oct 19, 2026
Reserved
Jul 19, 2026

Read the record on cve.org

Description

In 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.

Scores

CVSSScoreVectorSource
3.18.8 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:HLinux

Weaknesses

  • CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition

Affected Products

ProductVersions
LinuxLinux
  • 9b54e248d2644be71cb394eb85f31ad99e023a05 to before bd232801ef1d1fd985d2d4ca3cd1d888303ca86fAffected
  • 9b54e248d2644be71cb394eb85f31ad99e023a05 to before b1dfaa6f7a957726a6800135be3659fbe4bbf2a4Affected
  • 9b54e248d2644be71cb394eb85f31ad99e023a05 to before edbbe88f83b524434974e84808d3093199d67c24Affected
  • 9b54e248d2644be71cb394eb85f31ad99e023a05 to before c8cc238093ca6c99267032f6cfe78f59389f3157Affected
LinuxLinux
  • 6.11Affected
  • before 6.11Not affected
  • 6.12.93 through 6.12.*Not affected
  • 6.18.35 through 6.18.*Not affected
  • 7.0.12 through 7.0.*Not affected
  • 7.1 and laterNot affected

References

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