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CVE-2026-23401 affects the Linux kernel's x86 KVM memory-management subsystem. When host userspace modifies a shadowed guest page-table entry to change its mapping from a memory slot to emulated memory-mapped I/O (MMIO), a subsequent guest page fault can cause KVM to install an MMIO shadow page-table entry (SPTE) without first removing the existing shadow-present SPTE. The faulty replacement path reaches mark_mmio_spte and triggers a kernel warning. The original implementation accounted for guest writes but not guest-memory modifications outside KVM's control. The issue was introduced in upstream Linux 5.13 and fixed in Linux 7.0-rc6; distribution kernels have separate backported fixes.
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31 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A Linux kernel KVM x86 memory-management flaw involving replacement of shadow page-table entries with emulated MMIO entries. Writes to guest memory outside KVM can trigger installation of an MMIO entry without first invalidating an existing present entry. The advisory rates it CVSS v3 5.5, with local access, low privileges, and high availability impact; no confidentiality or integrity impact is indicated.
A Linux kernel KVM x86/MMU vulnerability involving replacement of shadow page-table entries. If host userspace modifies a shadowed guest page-table entry to switch from a memory slot to emulated MMIO, KVM can install an MMIO entry without first clearing the existing shadow-present entry. The advisory rates the flaw medium severity, with CVSS v3 5.5 indicating local, low-privilege exploitation and high availability impact.
A Linux kernel KVM vulnerability that can lead to privilege escalation or denial of service due to improper shadow page table entry handling.
A Linux kernel KVM vulnerability that can lead to privilege escalation or denial of service due to improper shadow page table entry handling.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.