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Windows Hyper-V Guest-to-Host RCE via Out-of-Bounds Read

IdentifiersCVE-2026-45641CWE-843· Access of Resource Using…

CVE-2026-45641 is a Windows Hyper-V vulnerability described by Microsoft as an out-of-bounds read, with advisory context also characterizing it as a type confusion/out-of-bounds read issue. The flaw affects Windows Hyper-V and can be triggered from a guest VM context. Available advisory detail indicates that an attacker can send specially crafted file operation requests to VM hardware resources to reach the vulnerable condition. Successful exploitation allows code execution on the Hyper-V host, making this a guest-to-host escape scenario. Microsoft’s published CVSS v3.1 vector is AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation can result in code execution on the Windows Hyper-V host from a guest VM context. This breaks VM isolation and can enable compromise of the host server with high impact to confidentiality, integrity, and availability. In practical terms, the vulnerability can provide a guest-to-host escape path, which is especially significant on systems hosting untrusted or multi-tenant workloads.

Mitigation

If you can’t patch tonight, do this now.

No specific vendor mitigation beyond patching was provided in the supplied content. Until patches are applied, reduce exposure by limiting untrusted or low-trust guest workloads on affected Hyper-V hosts and isolating high-risk multi-tenant virtualization environments where possible.

Remediation

Patch, then assume compromise.

Apply Microsoft’s security update for CVE-2026-45641. Microsoft indicates customer action is required. Prioritize patching affected Windows Hyper-V hosts, particularly those running guest VMs for multi-tenant, externally supplied, or otherwise untrusted workloads.
PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType
Microsoft CorporationWindows 10 21h2operating_system
Microsoft CorporationWindows 10 22h2operating_system
Microsoft CorporationWindows 11 23h2operating_system
Microsoft CorporationWindows 11 24h2operating_system
Microsoft CorporationWindows 11 25h2operating_system
Microsoft CorporationWindows 11 26h1operating_system
Microsoft CorporationWindows Hyper-Voperating_system
Microsoft CorporationWindows Server 2022operating_system
Microsoft CorporationWindows Server 2025operating_system

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.
Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity1

Community discussion across Reddit, Mastodon, and other social sources.