SEPTEMBER 8, 2026
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Case File

CVE-2026-63937

HIGH · CVSS 8.8 EPSS 0.16%

Source: NVD + CISA KEV + EPSS · Published 2026-07-19 · Last synced 2026-08-18

CyberRota Analysis

AI-Generated

The vulnerability affects the Linux kernel's KVM (Kernel-based Virtual Machine) component, specifically in how it handles the Page State Change (PSC) buffer when reading entries and indices. The flaw could lead to Time-of-Check to Time-of-Use (TOCTOU) bugs, potentially allowing misbehaving guest systems to manipulate the buffer and compromise host security. Organizations utilizing KVM on Linux should prioritize patching this vulnerability to safeguard against potential exploitation.

CVE
CVE-2026-63937
Severity
HIGH
CVSS
8.8
EPSS
0.16%
Linux

Original NVD 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.