Security Advisory
CVE-2026-63937
8.8
HIGH
Vulnerability 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.
Published Date
July 19, 2026
Official Source
NIST NVD Advisory