# CVE-2026-47291: Microsoft Windows integer overflow in HTTP.sys

Source: https://junglewise.ai/threats/cve-2026-47291-microsoft-windows-integer-overflow-in-http-sys  
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-2026-47291 · Severity: critical · CVSS 9.8 · Published 2026-06-09

A critical vulnerability exists in the Windows component responsible for handling web traffic (HTTP.sys). This flaw allows a remote, unauthenticated attacker to run malicious code on a server or workstation over the network. An exploit could lead to a complete system takeover, data theft, or significant service disruption without any user interaction.

## Quick answers

**Is CVE-2026-47291 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-47291 being exploited in the wild.

**How severe is CVE-2026-47291?** Critical severity, with a CVSS score of 9.8, published 9 June 2026.

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

**Is there a fix for CVE-2026-47291?** A patch was published on 2026-06-09: Security updates made available by Microsoft. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-47291 attacked?** It is attacked over the network, in an operating system.

**Am I affected by CVE-2026-47291?** Check whether anything you run is named in the advisory. 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

This vulnerability is classified as an integer overflow (CWE-190) leading to a heap-based buffer overflow (CWE-122) within the Windows HTTP protocol stack (HTTP.sys). The flaw is triggered when the driver incorrectly handles specially crafted HTTP requests, resulting in memory corruption. Because HTTP.sys runs in kernel mode, successful exploitation allows for remote code execution (RCE) with high privileges. The attack vector is network-based, requires no authentication, and involves no user interaction, making it highly wormable. Microsoft has released security updates to address this issue.

## Affected products

- Microsoft Windows

## Timeline

- 2026-06-09: disclosed: Initial publication by Microsoft and NVD.
- 2026-06-09: patched: Security updates made available by Microsoft.

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-47291](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-47291)