# CVE-2026-45636: Microsoft Windows NTFS heap overflow

Source: https://junglewise.ai/threats/cve-2026-45636-microsoft-windows-ntfs-heap-overflow  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-09. Updated: 2026-06-09  
License: CC BY 4.0 with a link back

CVE-2026-45636 · Severity: high · CVSS 7.8 · Published 2026-06-09

A security vulnerability has been identified in the Windows NTFS file system, which is the primary system used by Windows to store and retrieve files on hard drives. An attacker who already has limited access to a computer could exploit this flaw to gain full control over the system, potentially leading to data theft or the installation of malicious software. This issue requires a user to perform a specific action, such as opening a malicious file, to trigger the exploit.

Technologies: [Microsoft Windows NTFS](https://junglewise.ai/threats/technologies/windows-ntfs). Vendors: [Microsoft](https://junglewise.ai/threats/vendors/microsoft).

## Quick answers

**Is CVE-2026-45636 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-45636 being exploited in the wild.

**How severe is CVE-2026-45636?** High severity, with a CVSS score of 7.8, published 9 June 2026.

**Which products and versions are affected?** Microsoft Windows NTFS.

**Is there a fix for CVE-2026-45636?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-45636 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-2026-45636?** Check whether you run Microsoft Windows NTFS. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A heap-based buffer overflow vulnerability (CWE-122) exists in the Microsoft Windows NTFS driver due to improper input validation (CWE-20). The vulnerability is triggered when the system processes specially crafted file system metadata. An attacker with local access can exploit this by convincing a user to interact with a malicious file or partition, leading to arbitrary code execution with elevated privileges. The attack vector is local, requiring user interaction (UI:R), and provides high impact to confidentiality, integrity, and availability. Microsoft has released information regarding this vulnerability via their Security Update Guide.

## Affected products

- Microsoft Windows NTFS

## Timeline

- 2026-06-09: disclosed: Vulnerability published by Microsoft and NVD.
- 2026-06-09: advisory: Microsoft Security Update Guide entry created.

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45636](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45636)

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