Copyright © 2012 Red Hat, Inc. All rights reserved. Moderate 2026-08-04T00:00:00 kernel: KVM: x86: Check for invalid/obsolete root *after* making MMU pages available 7.0 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H CWE-825

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.

A flaw was found in KVM in the Linux kernel. This vulnerability occurs due to improper validation of memory management unit (MMU) page roots after these pages are made available. An attacker could exploit this by triggering a scenario where KVM attempts to map memory into an invalid root, causing child shadow pages to inherit an invalid state. This violates KVM's internal integrity rules, potentially leading to system instability or a denial of service within the virtualized environment.

Red Hat Enterprise Linux 10 2026-07-24T00:00:00Z RHSA-2026:45114 kernel-0:6.12.0-211.39.1.el10_2 Red Hat Enterprise Linux 10.0 Extended Update Support 2026-07-31T00:00:00Z RHSA-2026:49030 kernel-0:6.12.0-55.94.1.el10_0 Red Hat Enterprise Linux 8 2026-07-24T00:00:00Z RHSA-2026:45116 kernel-rt-0:4.18.0-553.147.1.rt7.488.el8_10 Red Hat Enterprise Linux 8 2026-07-24T00:00:00Z RHSA-2026:45115 kernel-0:4.18.0-553.147.1.el8_10 Red Hat Enterprise Linux 8.8 Telecommunications Update Service 2026-07-29T00:00:00Z RHSA-2026:47869 kernel-0:4.18.0-477.156.1.el8_8 Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions 2026-07-29T00:00:00Z RHSA-2026:47869 kernel-0:4.18.0-477.156.1.el8_8 Red Hat Enterprise Linux 9 2026-07-24T00:00:00Z RHSA-2026:45192 kernel-0:5.14.0-687.30.1.el9_8 Red Hat Enterprise Linux 9 2026-07-24T00:00:00Z RHSA-2026:45192 kernel-0:5.14.0-687.30.1.el9_8 Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions 2026-07-31T00:00:00Z RHSA-2026:48386 kernel-0:5.14.0-427.141.1.el9_4 Red Hat Enterprise Linux 9.6 Extended Update Support 2026-07-31T00:00:00Z RHSA-2026:49031 kernel-0:5.14.0-570.131.1.el9_6 Red Hat Enterprise Linux 6 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel-rt Red Hat Enterprise Linux 9 Affected kernel-rt https://www.cve.org/CVERecord?id=CVE-2026-64561 https://nvd.nist.gov/vuln/detail/CVE-2026-64561 https://lore.kernel.org/linux-cve-announce/2026080401-CVE-2026-64561-d0d4@gregkh/T