PT-2026-61254 · Linux · Linux

CVE-2026-63937 · Published 2026-07-19 · Updated 2026-07-19

NVD

CVSS v3.1

8.8

High

Base vector

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

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.

Fix

Related Identifiers

CVE-2026-63937

Affected Products

Linux

References · 5

• https://nvd.nist.gov/vuln/detail/CVE-2026-63937 · Security Note
• https://git.kernel.org/stable/c/bd232801ef1d1fd985d2d4ca3cd1d888303ca86f · Note
• https://git.kernel.org/stable/c/c8cc238093ca6c99267032f6cfe78f59389f3157 · Note
• https://git.kernel.org/stable/c/b1dfaa6f7a957726a6800135be3659fbe4bbf2a4 · Note
• https://git.kernel.org/stable/c/edbbe88f83b524434974e84808d3093199d67c24 · Note