RHSA-2026:49030MediumCVSS 7.0

Red Hat Security Advisory: kernel security update

Published
July 31, 2026
Last Modified
July 31, 2026

🔗 CVE IDs covered (2)

CVE-2026-63807 →CVE-2025-40026 →

📋 Description

CVE-2025-40026 — kernel: KVM: x86: Don't (re)check L1 intercepts when completing userspace I/O CVE-2026-63807 — kernel: KVM: x86/mmu: Ensure hugepage is in by slot before checking max mapping level

🎯 Affected products200

  • Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0)
  • Red Hat Enterprise Linux Real Time EUS (v. 10.0)
  • Red Hat Enterprise Linux Real Time for NFV EUS (v. 10.0)
  • kernel-0:6.12.0-55.94.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • kernel-0:6.12.0-55.94.1.el10_0.ppc64le as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • kernel-0:6.12.0-55.94.1.el10_0.s390x as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • kernel-0:6.12.0-55.94.1.el10_0.src as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • kernel-0:6.12.0-55.94.1.el10_0.x86_64 as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • kernel-64k-0:6.12.0-55.94.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • kernel-64k-core-0:6.12.0-55.94.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • kernel-64k-debug-0:6.12.0-55.94.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • kernel-64k-debug-core-0:6.12.0-55.94.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • kernel-64k-debug-debuginfo-0:6.12.0-55.94.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • kernel-64k-debug-debuginfo-0:6.12.0-55.94.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • kernel-64k-debug-debuginfo-0:6.12.0-55.94.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0)
  • kernel-64k-debug-debuginfo-0:6.12.0-55.94.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux Real Time EUS (v. 10.0)
  • kernel-64k-debug-devel-0:6.12.0-55.94.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • kernel-64k-debug-devel-matched-0:6.12.0-55.94.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • kernel-64k-debug-modules-0:6.12.0-55.94.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • kernel-64k-debug-modules-core-0:6.12.0-55.94.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • kernel-64k-debug-modules-extra-0:6.12.0-55.94.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • kernel-64k-debuginfo-0:6.12.0-55.94.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • kernel-64k-debuginfo-0:6.12.0-55.94.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • kernel-64k-debuginfo-0:6.12.0-55.94.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0)
  • kernel-64k-debuginfo-0:6.12.0-55.94.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux Real Time EUS (v. 10.0)
  • kernel-64k-devel-0:6.12.0-55.94.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • kernel-64k-devel-matched-0:6.12.0-55.94.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • kernel-64k-modules-0:6.12.0-55.94.1.el10_0.aarch64 as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0)
  • +170 more not shown

✅ Remediation

For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 The system must be rebooted for this update to take effect. Red Hat recommends treating all kernel errata as security-relevant. Given the kernel's fundamental role, any bug has a higher chance of impacting system security, even if that impact only becomes clear after a fix is published. Therefore, Red Hat prioritizes delivering fixes that improve our customers' overall security posture. Because of this proactive approach, a patch may be associated with a CVE assignment at a future date. Retroactive CVE assignments are always documented in the corresponding errata and on Red Hat's CVE pages. We strongly advise against delaying updates, as doing so may leave your system exposed when protections are already available. Workaround: This vulnerability can be mitigated by disabling nested virtualization. Create a file in `/etc/modprobe.d/` with a descriptive name, such as `cve-2026-53359-mitigation.conf`. In that file, disable nested virtualization for the `kvm_intel` and `kvm_amd` kernel modules: ``` options kvm-intel nested=0 options kvm-amd nested=0 ``` Use `lsmod` to determine if either module is already loaded. If so, remove loaded modules with `modprobe -r`. To validate that nested virtualization is disabled, read the files `/sys/module/kvm_intel/parameters/nested` and `/sys/module/kvm_amd/parameters/nested`. If these modules are loaded, those files should read `N` to indicate that the feature is disabled. In OpenShift 4, a MachineConfig can be utilized to create a modprobe configuration allowing control of the module on applicable nodes. See the following article for an example. https://access.redhat.com/solutions/6979679

🔗 References (5)