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CVE-2025-40026 is an instruction-emulation flaw in the Linux kernel's KVM x86 subsystem. When completing an L2 guest instruction following a userspace I/O exit, KVM incorrectly rechecks L1 intercepts after already committing to and emulating the I/O operation. If the L1 guest or host userspace changes I/O permission bitmaps during that exit, KVM can incorrectly treat the completed access as intercepted, leaving instruction emulation incomplete and vcpu->arch.pio.count nonzero. A syzkaller reproducer triggered a kernel warning in emulator_pio_in_out(). The flaw was introduced in Linux 3.0.
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No public exploit code observed for this vulnerability.
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43 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A vulnerability in the Linux kernel's x86 KVM handling of L1 intercepts when completing userspace I/O affects RHEL 7 kernel-rt packages. The listed CVSS v3 score is 7.9, indicating local exploitation requiring low privileges, with high availability impact and low confidentiality and integrity impacts. Red Hat advisory RHSA-2026:78843 provides a security update. Nessus detects affected package versions rather than directly testing exploitation.
A Linux kernel KVM x86 vulnerability affecting RHEL 7 kernel packages, addressed by correcting L1 intercept checks when completing userspace I/O. The listed CVSS v3 score is 7.9, indicating local exploitation requiring low privileges, with high availability impact and low confidentiality and integrity impacts. Nessus detects affected package versions rather than testing exploitation.
A Linux kernel KVM x86 vulnerability involving incorrect rechecking of nested-virtualization I/O intercepts when completing userspace I/O. A syzkaller reproducer triggered incomplete instruction emulation and a kernel warning. The advisory assigns a CVSS v3 base score of 7.9 and identifies affected Google COS kernel packages.
A Linux kernel KVM x86 vulnerability involving rechecking L1 intercepts while completing userspace I/O, addressed by the Rocky Linux 8 security advisory.
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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.