CVE-2026-64561

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

Published Aug 4, 2026 CVSS 3.1 · 8.8 High EPSS < 1% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4745-1 linux-6.12 security update
Debian DLA Debian DLA DLA-4777-1 linux security update
Debian DSA Debian DSA DSA-6415-1 linux security update
Ubuntu USN Ubuntu USN USN-8781-1 Linux kernel (NVIDIA Tegra) vulnerabilities
Ubuntu USN Ubuntu USN USN-8887-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8888-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-8889-1 Linux kernel (OEM) vulnerabilities
Ubuntu USN Ubuntu USN USN-8887-2 Linux kernel (AWS) vulnerabilities
Ubuntu USN Ubuntu USN USN-8888-2 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-8887-3 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8917-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8918-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-8961-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-9003-1 Linux kernel (NVIDIA) vulnerabilities
Ubuntu USN Ubuntu USN USN-9024-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-9025-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-9026-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-9029-1 Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN Ubuntu USN USN-9040-1 Linux kernel (Low Latency NVIDIA) vulnerabilities
Ubuntu USN Ubuntu USN USN-9043-1 Linux kernel (NVIDIA) vulnerabilities
Ubuntu USN Ubuntu USN USN-9066-1 Linux kernel (HWE) vulnerabilities
History
Type Values Removed Values Added
CPEs cpe:2.3:o:linux:linux_kernel:7.2:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.2:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.2:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.2:rc4:*:*:*:*:*:*
Type Values Removed Values Added
Weaknesses CWE-362
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

cvssV3_1

{'score': 8.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H'}

Type Values Removed Values Added
Weaknesses CWE-825
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

threat_severity

Important

Type Values Removed Values Added
Description 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.
Title KVM: x86: Check for invalid/obsolete root *after* making MMU pages available
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
Linux
Published
Updated
Oct 19, 2026, 8:48 PM
Reserved
Jul 19, 2026, 3:36 PM
Status
Analyzed
Published
Aug 4, 2026, 7:16 AM
Modified
Nov 13, 2026, 6:19 PM
Severity
Important
Public date
Aug 4, 2026, 12:00 AM