CVE-2026-97813 Overview
CVE-2026-97813 is a heap-based buffer overflow [CWE-122] in Windows Hyper-V that allows an authorized attacker to disclose information over a network. Microsoft disclosed the vulnerability through its Security Update Guide. The flaw affects the memory management of Hyper-V components exposed to network-reachable requests from authenticated principals. Successful exploitation results in confidentiality impact without affecting integrity or availability of the host.
Critical Impact
An authorized attacker with network access to Hyper-V can trigger a heap overflow condition to read sensitive memory contents from the hypervisor host.
Affected Products
- Windows Hyper-V (specific build list published in the Microsoft Security Update Guide)
- Windows Server editions shipping the Hyper-V role
- Windows client editions with Hyper-V enabled
Discovery Timeline
- 2026-10-13 - CVE-2026-97813 published to the National Vulnerability Database
- 2026-10-13 - Last updated in NVD database
Technical Details for CVE-2026-97813
Vulnerability Analysis
The vulnerability is a heap-based buffer overflow in Windows Hyper-V. The defect sits in code paths reachable by an authenticated principal who can send crafted requests to the hypervisor over a network. When the vulnerable routine processes an attacker-controlled input, it writes beyond the allocated heap buffer boundary. The resulting out-of-bounds access exposes adjacent heap memory to the attacker.
The confidentiality impact is high while integrity and availability are not affected, which indicates the bug yields a memory disclosure primitive rather than code execution or crash. An attacker gains read access to residual heap contents such as pointers, session identifiers, or guest or host memory fragments. Repeated triggering can be used to progressively map memory layout or recover cryptographic material.
Exploitation requires low privileges and no user interaction. The attack complexity is low and the scope is unchanged, meaning the compromised component and the impacted component share the same security authority.
Root Cause
The root cause is improper validation of a size or length value before a heap write operation in a Hyper-V component. The affected routine allocates a buffer based on one computation and then copies data using a different, attacker-influenced length. Microsoft has not published the specific function names or offsets in public documentation.
Attack Vector
The attack vector is network. An authenticated attacker sends a specially crafted message to the Hyper-V management or virtualization service. The service parses the message and performs the vulnerable heap operation. The response, logs, or subsequent service state returns heap memory contents to the attacker. See the Microsoft Security Update Guide entry for CVE-2026-97813 for authoritative details.
Detection Methods for CVE-2026-97813
Indicators of Compromise
- Unexpected authenticated connections to Hyper-V management endpoints from non-administrative accounts.
- Hyper-V service process (vmms.exe, vmwp.exe) crashes or abnormal memory allocation events in Windows Event Log.
- Outbound traffic volume anomalies from Hyper-V hosts correlated with sustained authenticated sessions.
Detection Strategies
- Monitor Windows Hyper-V-Worker and Hyper-V-VMMS operational logs for malformed request errors or parser exceptions.
- Alert on repeated authentication to Hyper-V services from a single principal within short time windows.
- Correlate Hyper-V service exceptions with network session metadata to identify probing patterns.
Monitoring Recommendations
- Enable auditing on Hyper-V administrative role assignments and track changes to the Hyper-V Administrators group.
- Collect host EDR telemetry for vmms.exe and virtual machine worker processes to surface anomalous memory access patterns.
- Forward Hyper-V and WMI event channels to a SIEM for retention and cross-host correlation.
How to Mitigate CVE-2026-97813
Immediate Actions Required
- Apply the Microsoft security update referenced in the Security Update Guide to all Hyper-V hosts.
- Inventory all systems with the Hyper-V role enabled, including client editions, and prioritize patching for internet-adjacent hosts.
- Restrict Hyper-V management access to a dedicated administrative network segment.
Patch Information
Microsoft published the fix through its monthly security update channel. Review the Microsoft Security Update Guide entry for CVE-2026-97813 for the authoritative list of affected builds, KB article identifiers, and update packages. Apply the vendor-supplied cumulative update that corresponds to each host's Windows build.
Workarounds
- Remove or disable the Hyper-V role on systems that do not require virtualization until patches can be applied.
- Enforce network-level authentication and firewall rules that restrict access to Hyper-V management interfaces to trusted administrative hosts.
- Reduce the number of accounts holding Hyper-V Administrators or equivalent delegated rights to minimize the authenticated attack surface.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
