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Fencer Vulns
high 8.8

CVE-2026-64561 json

KVM: x86: Check for invalid/obsolete root *after* making MMU pages available

published 2026-08-04 3 mo ago modified 2026-11-03 5 d ago also EUVD-2026-52602

cvss
8.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 19%
public exploits
0
none known

Summary

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

KVM: x86: Check for invalid/obsolete root *after* making MMU pages available

Check for a "stale" page fault, i.e. for an invalid and/or obsolete root, after making MMU pages available for the shadow MMU. If reclaiming shadow pages zaps an in-use root, i.e. marks it invalid, then KVM will attempt to map memory into an invalid root. On its own, populating an invalid root is "fine", but because child shadow pages inherit their parent's role, any children created during the map/fetch will be created as invalid pages, thus violating KVM's invariant that invalid pages are never on the list of active MMU pages.

Note, the underlying flaw has existed since KVM first started tracking invalid roots in 2008 (commit 2e53d63acba7, "KVM: MMU: ignore zapped root pagetables"), but the true badness only came along in 2020 (Linux 5.9) with the invariant that invalid shadow pages can't be on the list of active pages.

Note #2, inheriting role.invalid when creating child shadow pages is also far from ideal; that flaw will be addressed separately.

Patch / fix

  • Linux Linux 5.15.218, 6.1.183, 6.6.148, 6.12.101, 6.18.42, 7.1.6, 7.2
  • linux Debian 12 6.1.187-1
  • linux Debian 13 6.12.101-1
  • linux Debian 14 7.1.6-1
  • linux-6.12 Debian 12 6.12.101-1~deb12u1

debian advisories DEBIAN-CVE-2026-64561

  • linux Ubuntu 22.04 LTS 5.15.0-202.212
  • linux Ubuntu 24.04 LTS 6.8.0-147.147
  • linux Ubuntu 26.04 LTS 7.0.0-38.38
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1119.126
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1067.70
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1014.14
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1120.130
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1071.79

ubuntu advisories UBUNTU-CVE-2026-64561

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel RHEL 9 5.14.0-687.30.1.el9_8
  • rv RHEL 9 5.14.0-687.30.1.el9_8
  • perf RHEL 9 5.14.0-687.30.1.el9_8
  • rtla RHEL 9 5.14.0-687.30.1.el9_8
  • libperf RHEL 9 5.14.0-687.30.1.el9_8
  • kernel-rt RHEL 9 5.14.0-687.30.1.el9_8
  • kernel-64k RHEL 9 5.14.0-687.30.1.el9_8
  • kernel-core RHEL 9 5.14.0-687.30.1.el9_8

red hat advisories RHSA-2026:49030RHSA-2026:49031RHSA-2026:48386RHSA-2026:47869RHSA-2026:45192RHSA-2026:45115

  • kernel-default SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Live Patching 15 SP6 +1 more 6.4.0-150600.23.130.1
  • kernel-livepatch-SLE16_Update_15 SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 3-160000.1.1
  • kernel-livepatch-SLE16_Update_5 SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 11-160000.1.1
  • kernel-livepatch-SLE16_Update_4 SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 12-160000.1.1
  • kernel-livepatch-SLE16_Update_3 SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 13-160000.1.1
  • kernel-livepatch-SLE16_Update_2 SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 14-160000.1.1
  • kernel-livepatch-SLE16_Update_10 SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 7-160000.1.1
  • kernel-livepatch-SLE16_Update_9 SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 7-160000.1.1

suse advisories SUSE-SU-2026:3602-1SUSE-SU-2026:23951-1SUSE-SU-2026:23968-1SUSE-SU-2026:23944-1SUSE-SU-2026:23967-1SUSE-SU-2026:23942-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.38.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-azure openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.38.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.38.1

opensuse advisories openSUSE-SU-2026:21910-1openSUSE-SU-2026:21555-1openSUSE-SU-2026:11476-1

  • kernel AlmaLinux 10 6.12.0-211.39.1.el10_2
  • rv AlmaLinux 10 6.12.0-211.39.1.el10_2
  • perf AlmaLinux 10 6.12.0-211.39.1.el10_2
  • rtla AlmaLinux 10 6.12.0-211.39.1.el10_2
  • libperf AlmaLinux 10 6.12.0-211.39.1.el10_2
  • kernel-rt AlmaLinux 10 6.12.0-211.39.1.el10_2
  • kernel-64k AlmaLinux 10 6.12.0-211.39.1.el10_2
  • kernel-core AlmaLinux 10 6.12.0-211.39.1.el10_2

almalinux advisories ALSA-2026:45114ALSA-2026:45115ALSA-2026:45116ALSA-2026:45192

  • kernel Azure Linux 3.0 6.6.150.1-1

azure linux advisories AZL-94368

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-64561 updated cvss 7.0

kernel: KVM: x86: Check for invalid/obsolete root *after* making MMU pages available

  • Red Hat Enterprise Linux 9 kernel-rt, kernel-rt-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +12 more
    affected: workaround, no fix available
  • Red Hat CodeReady Linux Builder EUS (v.9.6) libperf 5.14.0-570.131.1.el9_6, kernel-debuginfo-common-s390x 5.14.0-570.131.1.el9_6, kernel-debuginfo-common-x86_64 5.14.0-570.131.1.el9_6, kernel-debuginfo-common-aarch64 5.14.0-570.131.1.el9_6, kernel-debuginfo-common-ppc64le 5.14.0-570.131.1.el9_6
    fixed: vendor fix RHSA-2026:49031
  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-687.30.1.el9_8, perf 5.14.0-687.30.1.el9_8, rtla 5.14.0-687.30.1.el9_8, python3-perf 5.14.0-687.30.1.el9_8, kernel-devel-matched 5.14.0-687.30.1.el9_8, kernel-64k-devel-matched 5.14.0-687.30.1.el9_8, +7 more
    fixed: vendor fix RHSA-2026:45192
  • Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-211.39.1.el10_2, perf 6.12.0-211.39.1.el10_2, rtla 6.12.0-211.39.1.el10_2, python3-perf 6.12.0-211.39.1.el10_2, kernel-devel-matched 6.12.0-211.39.1.el10_2, kernel-64k-devel-matched 6.12.0-211.39.1.el10_2, +7 more
    fixed: vendor fix RHSA-2026:45114
  • Red Hat Enterprise Linux AppStream E4S (v.9.4) rv 5.14.0-427.141.1.el9_4, perf 5.14.0-427.141.1.el9_4, rtla 5.14.0-427.141.1.el9_4, kernel-devel-matched 5.14.0-427.141.1.el9_4, kernel-64k-devel-matched 5.14.0-427.141.1.el9_4, kernel-debug-devel-matched 5.14.0-427.141.1.el9_4, +6 more
    fixed: vendor fix RHSA-2026:48386
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) rv 6.12.0-55.94.1.el10_0, perf 6.12.0-55.94.1.el10_0, rtla 6.12.0-55.94.1.el10_0, python3-perf 6.12.0-55.94.1.el10_0, kernel-devel-matched 6.12.0-55.94.1.el10_0, kernel-64k-devel-matched 6.12.0-55.94.1.el10_0, +7 more
    fixed: vendor fix RHSA-2026:49030
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) rv 5.14.0-570.131.1.el9_6, perf 5.14.0-570.131.1.el9_6, rtla 5.14.0-570.131.1.el9_6, python3-perf 5.14.0-570.131.1.el9_6, kernel-devel-matched 5.14.0-570.131.1.el9_6, kernel-64k-devel-matched 5.14.0-570.131.1.el9_6, +7 more
    fixed: vendor fix RHSA-2026:49031
  • Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-553.147.1.el8_10, kernel 4.18.0-553.147.1.el8_10, bpftool 4.18.0-553.147.1.el8_10, kernel-core 4.18.0-553.147.1.el8_10, kernel-tools 4.18.0-553.147.1.el8_10, python3-perf 4.18.0-553.147.1.el8_10, +15 more
    fixed: vendor fix RHSA-2026:45115
show 24 more
  • Red Hat Enterprise Linux BaseOS (v. 9) kernel 5.14.0-687.30.1.el9_8, kernel-64k 5.14.0-687.30.1.el9_8, kernel-core 5.14.0-687.30.1.el9_8, kernel-tools 5.14.0-687.30.1.el9_8, kernel-modules 5.14.0-687.30.1.el9_8, kernel-64k-core 5.14.0-687.30.1.el9_8, +27 more
    fixed: vendor fix RHSA-2026:45192
  • Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-211.39.1.el10_2, kernel-64k 6.12.0-211.39.1.el10_2, kernel-core 6.12.0-211.39.1.el10_2, kernel-tools 6.12.0-211.39.1.el10_2, kernel-modules 6.12.0-211.39.1.el10_2, kernel-64k-core 6.12.0-211.39.1.el10_2, +28 more
    fixed: vendor fix RHSA-2026:45114
  • Red Hat Enterprise Linux BaseOS E4S (v.8.8) perf 4.18.0-477.156.1.el8_8, kernel 4.18.0-477.156.1.el8_8, bpftool 4.18.0-477.156.1.el8_8, kernel-core 4.18.0-477.156.1.el8_8, kernel-tools 4.18.0-477.156.1.el8_8, python3-perf 4.18.0-477.156.1.el8_8, +9 more
    fixed: vendor fix RHSA-2026:47869
  • Red Hat Enterprise Linux BaseOS E4S (v.9.4) bpftool 7.3.0-427.141.1.el9_4, kernel 5.14.0-427.141.1.el9_4, kernel-64k 5.14.0-427.141.1.el9_4, kernel-core 5.14.0-427.141.1.el9_4, kernel-tools 5.14.0-427.141.1.el9_4, python3-perf 5.14.0-427.141.1.el9_4, +28 more
    fixed: vendor fix RHSA-2026:48386
  • Red Hat Enterprise Linux BaseOS EUS (v. 10.0) kernel 6.12.0-55.94.1.el10_0, kernel-64k 6.12.0-55.94.1.el10_0, kernel-core 6.12.0-55.94.1.el10_0, kernel-tools 6.12.0-55.94.1.el10_0, kernel-modules 6.12.0-55.94.1.el10_0, kernel-64k-core 6.12.0-55.94.1.el10_0, +27 more
    fixed: vendor fix RHSA-2026:49030
  • Red Hat Enterprise Linux BaseOS EUS (v.9.6) kernel 5.14.0-570.131.1.el9_6, kernel-64k 5.14.0-570.131.1.el9_6, kernel-core 5.14.0-570.131.1.el9_6, kernel-tools 5.14.0-570.131.1.el9_6, kernel-modules 5.14.0-570.131.1.el9_6, kernel-64k-core 5.14.0-570.131.1.el9_6, +27 more
    fixed: vendor fix RHSA-2026:49031
  • Red Hat Enterprise Linux BaseOS TUS (v.8.8) perf 4.18.0-477.156.1.el8_8, kernel 4.18.0-477.156.1.el8_8, bpftool 4.18.0-477.156.1.el8_8, kernel-core 4.18.0-477.156.1.el8_8, kernel-tools 4.18.0-477.156.1.el8_8, python3-perf 4.18.0-477.156.1.el8_8, +8 more
    fixed: vendor fix RHSA-2026:47869
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) libperf 5.14.0-687.30.1.el9_8, kernel-debuginfo-common-s390x 5.14.0-687.30.1.el9_8, kernel-debuginfo-common-x86_64 5.14.0-687.30.1.el9_8, kernel-debuginfo-common-aarch64 5.14.0-687.30.1.el9_8, kernel-debuginfo-common-ppc64le 5.14.0-687.30.1.el9_8
    fixed: vendor fix RHSA-2026:45192
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-211.39.1.el10_2, kernel-debuginfo-common-s390x 6.12.0-211.39.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.39.1.el10_2, kernel-debuginfo-common-aarch64 6.12.0-211.39.1.el10_2, kernel-debuginfo-common-ppc64le 6.12.0-211.39.1.el10_2
    fixed: vendor fix RHSA-2026:45114
  • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) libperf 6.12.0-55.94.1.el10_0, kernel-debuginfo-common-s390x 6.12.0-55.94.1.el10_0, kernel-debuginfo-common-x86_64 6.12.0-55.94.1.el10_0, kernel-debuginfo-common-aarch64 6.12.0-55.94.1.el10_0, kernel-debuginfo-common-ppc64le 6.12.0-55.94.1.el10_0
    fixed: vendor fix RHSA-2026:49030
  • Red Hat Enterprise Linux CRB (v. 8) kernel-debuginfo-common-x86_64 4.18.0-553.147.1.el8_10, kernel-debuginfo-common-aarch64 4.18.0-553.147.1.el8_10, kernel-debuginfo-common-ppc64le 4.18.0-553.147.1.el8_10
    fixed: vendor fix RHSA-2026:45115
  • Red Hat Enterprise Linux NFV (v. 8) kernel-rt 4.18.0-553.147.1.rt7.488.el8_10, kernel-rt-kvm 4.18.0-553.147.1.rt7.488.el8_10, kernel-rt-core 4.18.0-553.147.1.rt7.488.el8_10, kernel-rt-modules 4.18.0-553.147.1.rt7.488.el8_10, kernel-rt-debug-kvm 4.18.0-553.147.1.rt7.488.el8_10, kernel-rt-debug-core 4.18.0-553.147.1.rt7.488.el8_10, +4 more
    fixed: vendor fix RHSA-2026:45116
  • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt 5.14.0-687.30.1.el9_8, kernel-rt-64k 5.14.0-687.30.1.el9_8, kernel-rt-core 5.14.0-687.30.1.el9_8, kernel-rt-modules 5.14.0-687.30.1.el9_8, kernel-rt-64k-core 5.14.0-687.30.1.el9_8, kernel-rt-debug-core 5.14.0-687.30.1.el9_8, +14 more
    fixed: vendor fix RHSA-2026:45192
  • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-211.39.1.el10_2, kernel-rt-64k 6.12.0-211.39.1.el10_2, kernel-rt-core 6.12.0-211.39.1.el10_2, kernel-rt-modules 6.12.0-211.39.1.el10_2, kernel-rt-64k-core 6.12.0-211.39.1.el10_2, kernel-rt-debug-core 6.12.0-211.39.1.el10_2, +14 more
    fixed: vendor fix RHSA-2026:45114
  • Red Hat Enterprise Linux Real Time E4S (v.9.4) kernel-rt 5.14.0-427.141.1.el9_4, kernel-rt-core 5.14.0-427.141.1.el9_4, kernel-rt-modules 5.14.0-427.141.1.el9_4, kernel-rt-debug-core 5.14.0-427.141.1.el9_4, kernel-rt-modules-core 5.14.0-427.141.1.el9_4, kernel-rt-debug-modules 5.14.0-427.141.1.el9_4, +4 more
    fixed: vendor fix RHSA-2026:48386
  • Red Hat Enterprise Linux Real Time EUS (v. 10.0) kernel-rt 6.12.0-55.94.1.el10_0, kernel-rt-64k 6.12.0-55.94.1.el10_0, kernel-rt-core 6.12.0-55.94.1.el10_0, kernel-rt-modules 6.12.0-55.94.1.el10_0, kernel-rt-64k-core 6.12.0-55.94.1.el10_0, kernel-rt-debug-core 6.12.0-55.94.1.el10_0, +14 more
    fixed: vendor fix RHSA-2026:49030
  • Red Hat Enterprise Linux Real Time EUS (v.9.6) kernel-rt 5.14.0-570.131.1.el9_6, kernel-rt-64k 5.14.0-570.131.1.el9_6, kernel-rt-core 5.14.0-570.131.1.el9_6, kernel-rt-modules 5.14.0-570.131.1.el9_6, kernel-rt-64k-core 5.14.0-570.131.1.el9_6, kernel-rt-debug-core 5.14.0-570.131.1.el9_6, +14 more
    fixed: vendor fix RHSA-2026:49031
  • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt 5.14.0-687.30.1.el9_8, kernel-rt-core 5.14.0-687.30.1.el9_8, kernel-rt-modules 5.14.0-687.30.1.el9_8, kernel-rt-debug-core 5.14.0-687.30.1.el9_8, kernel-rt-modules-core 5.14.0-687.30.1.el9_8, kernel-rt-debug-modules 5.14.0-687.30.1.el9_8, +4 more
    fixed: vendor fix RHSA-2026:45192
  • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-211.39.1.el10_2, kernel-rt-core 6.12.0-211.39.1.el10_2, kernel-rt-modules 6.12.0-211.39.1.el10_2, kernel-rt-debug-core 6.12.0-211.39.1.el10_2, kernel-rt-modules-core 6.12.0-211.39.1.el10_2, kernel-rt-debug-modules 6.12.0-211.39.1.el10_2, +4 more
    fixed: vendor fix RHSA-2026:45114
  • Red Hat Enterprise Linux Real Time for NFV E4S (v.9.4) kernel-rt 5.14.0-427.141.1.el9_4, kernel-rt-kvm 5.14.0-427.141.1.el9_4, kernel-rt-core 5.14.0-427.141.1.el9_4, kernel-rt-modules 5.14.0-427.141.1.el9_4, kernel-rt-debug-kvm 5.14.0-427.141.1.el9_4, kernel-rt-debug-core 5.14.0-427.141.1.el9_4, +6 more
    fixed: vendor fix RHSA-2026:48386
  • Red Hat Enterprise Linux Real Time for NFV EUS (v. 10.0) kernel-rt 6.12.0-55.94.1.el10_0, kernel-rt-kvm 6.12.0-55.94.1.el10_0, kernel-rt-core 6.12.0-55.94.1.el10_0, kernel-rt-modules 6.12.0-55.94.1.el10_0, kernel-rt-debug-kvm 6.12.0-55.94.1.el10_0, kernel-rt-debug-core 6.12.0-55.94.1.el10_0, +6 more
    fixed: vendor fix RHSA-2026:49030
  • Red Hat Enterprise Linux Real Time for NFV EUS (v.9.6) kernel-rt 5.14.0-570.131.1.el9_6, kernel-rt-kvm 5.14.0-570.131.1.el9_6, kernel-rt-core 5.14.0-570.131.1.el9_6, kernel-rt-modules 5.14.0-570.131.1.el9_6, kernel-rt-debug-kvm 5.14.0-570.131.1.el9_6, kernel-rt-debug-core 5.14.0-570.131.1.el9_6, +6 more
    fixed: vendor fix RHSA-2026:49031
  • Red Hat Enterprise Linux RT (v. 8) kernel-rt 4.18.0-553.147.1.rt7.488.el8_10, kernel-rt-core 4.18.0-553.147.1.rt7.488.el8_10, kernel-rt-modules 4.18.0-553.147.1.rt7.488.el8_10, kernel-rt-debug-core 4.18.0-553.147.1.rt7.488.el8_10, kernel-rt-debug-modules 4.18.0-553.147.1.rt7.488.el8_10, kernel-rt-modules-extra 4.18.0-553.147.1.rt7.488.el8_10, +2 more
    fixed: vendor fix RHSA-2026:45116
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
24 d ago

Exploit prediction

0.27% chance of exploitation in the next 30 days, higher than 19% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 8.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Weakness
  • CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.