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Vulnerability · Published Jul 19, 2026 · Assigned by Linux

CVE-2026-63937KVM: SEV: Use READ_ONCE() when reading entries/indices from PSC buffer

High 8.8

In plain English

A high-severity security flaw in Linux from Linux. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 3% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)8.8High
Exploit odds (30 days)0.1%top 97.0% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:13linux6.12.94-1DEBIAN-CVE-2026-63937
Debian:14linux7.0.12-1DEBIAN-CVE-2026-63937
Ubuntu:26.04:LTSlinux7.0.0-28.28UBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-allwinner-5.19no fix listedUBUNTU-CVE-2026-63937
Ubuntu:26.04:LTSlinux-aws7.0.0-1009.9UBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-aws-5.19no fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-aws-6.14no fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-aws-6.17no fix listedUBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-aws-6.2no fix listedUBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-aws-6.5no fix listedUBUNTU-CVE-2026-63937
Ubuntu:26.04:LTSlinux-azure7.0.0-1010.10UBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-azure-5.19no fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-azure-6.11no fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-azure-6.14no fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-azure-6.17no fix listedUBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-azure-6.2no fix listedUBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-azure-6.5no fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-azure-7.07.0.0-1014.14~24.04.1UBUNTU-CVE-2026-63937
Ubuntu:26.04:LTSlinux-azure-fde7.0.0-1009.9UBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-azure-fde-5.19no fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-azure-fde-6.14no fix listedUBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-azure-fde-6.2no fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-azure-fde-7.07.0.0-1013.13~24.04.1UBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-azure-nvidia-6.14no fix listedUBUNTU-CVE-2026-63937
Ubuntu:26.04:LTSlinux-gcp7.0.0-1008.8UBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-gcp-5.19no fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-gcp-6.11no fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-gcp-6.14no fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-gcp-6.17no fix listedUBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-gcp-6.2no fix listedUBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-gcp-6.5no fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-gcp-7.07.0.0-1011.11~24.04.1UBUNTU-CVE-2026-63937
Ubuntu:26.04:LTSlinux-gke7.0.0-1003.4UBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-hwe-5.19no fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-hwe-6.11no fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-hwe-6.14no fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-hwe-6.17no fix listedUBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-hwe-6.2no fix listedUBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-hwe-6.5no fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-hwe-7.07.0.0-28.28~24.04.1UBUNTU-CVE-2026-63937
Ubuntu:26.04:LTSlinux-ibm7.0.0-1010.10UBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-intel-iot-realtimeno fix listedUBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-lowlatency-hwe-5.19no fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-lowlatency-hwe-6.11no fix listedUBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.2no fix listedUBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.5no fix listedUBUNTU-CVE-2026-63937
Ubuntu:26.04:LTSlinux-nvidia7.0.0-1016.16UBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-nvidia-6.11no fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-nvidia-6.17no fix listedUBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-nvidia-6.2no fix listedUBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-nvidia-6.5no fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-nvidia-7.07.0.0-1016.16~24.04.1UBUNTU-CVE-2026-63937
Ubuntu:26.04:LTSlinux-nvidia-bos7.0.0-2016.16UBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-oem-5.17no fix listedUBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-oem-6.0no fix listedUBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-oem-6.1no fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-oem-6.11no fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-oem-6.14no fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-oem-6.17no fix listedUBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-oem-6.5no fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-oem-6.8no fix listedUBUNTU-CVE-2026-63937
Ubuntu:26.04:LTSlinux-oem-7.07.0.0-1009.9UBUNTU-CVE-2026-63937
Ubuntu:26.04:LTSlinux-oracle7.0.0-1008.8UBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-oracle-6.14no fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-oracle-6.17no fix listedUBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-oracle-6.5no fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-oracle-7.07.0.0-1011.11~24.04.1UBUNTU-CVE-2026-63937
Ubuntu:26.04:LTSlinux-raspi7.0.0-1015.15UBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-raspi-realtimeno fix listedUBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-63937
Ubuntu:26.04:LTSlinux-realtime7.0.0-28.28.1UBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-63937
Ubuntu:26.04:LTSlinux-riscv7.0.0-28.28.1UBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-riscv-5.19no fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-riscv-6.14no fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-riscv-6.17no fix listedUBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-riscv-6.5no fix listedUBUNTU-CVE-2026-63937
Ubuntu:24.04:LTSlinux-riscv-7.07.0.0-28.28.1~24.04.3UBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-starfive-5.19no fix listedUBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-starfive-6.2no fix listedUBUNTU-CVE-2026-63937
Ubuntu:22.04:LTSlinux-starfive-6.5no fix listedUBUNTU-CVE-2026-63937

Affected products (as reported)

VendorProductVersions
Linux Linux 9b54e248d2644be71cb394eb85f31ad99e023a05 – before bd232801ef1d1fd985d2d4ca3cd1d888303ca86f9b54e248d2644be71cb394eb85f31ad99e023a05 – before b1dfaa6f7a957726a6800135be3659fbe4bbf2a49b54e248d2644be71cb394eb85f31ad99e023a05 – before edbbe88f83b524434974e84808d3093199d67c249b54e248d2644be71cb394eb85f31ad99e023a05 – before c8cc238093ca6c99267032f6cfe78f59389f3157
Linux Linux 6.11

Weakness: CWE-367 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

References