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CVE-2026-63937

Опубликовано: 19 июл. 2026
Источник: redhat
CVSS3: 5.5

Описание

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.

A flaw was found in the Linux kernel's Kernel-based Virtual Machine (KVM) with Secure Encrypted Virtualization (SEV). This time-of-check to time-of-use (TOCTOU) vulnerability exists when KVM processes the guest-accessible Page State Change (PSC) buffer. A misbehaving guest could exploit this timing issue by modifying the buffer after it has been checked but before it is used, potentially leading to an impact on the integrity of the virtualized environment.

Затронутые пакеты

ПлатформаПакетСостояниеРекомендацияРелиз
Red Hat Enterprise Linux 10kernelFix deferred
Red Hat Enterprise Linux 6kernelNot affected
Red Hat Enterprise Linux 7kernelNot affected
Red Hat Enterprise Linux 7kernel-rtNot affected
Red Hat Enterprise Linux 8kernelNot affected
Red Hat Enterprise Linux 8kernel-rtNot affected
Red Hat Enterprise Linux 9kernelFix deferred
Red Hat Enterprise Linux 9kernel-rtFix deferred

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Дополнительная информация

Статус:

Moderate
Дефект:
CWE-367
https://bugzilla.redhat.com/show_bug.cgi?id=2502399kernel: KVM: SEV: Use READ_ONCE() when reading entries/indices from PSC buffer

5.5 Medium

CVSS3

Связанные уязвимости

CVSS3: 8.8
ubuntu
14 дней назад

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.

CVSS3: 8.8
nvd
14 дней назад

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.

CVSS3: 8.8
debian
14 дней назад

In the Linux kernel, the following vulnerability has been resolved: K ...

CVSS3: 8.8
github
14 дней назад

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.

5.5 Medium

CVSS3