CVE intelligence

CVE-2026-47291

Vulnerability intelligence

Published Jun 9, 2026Sources checked Nov 12, 2026

9.8CRITICALCVSS out of 10

What this means

Review the available evidence

CVE-2026-47291 and is rated Critical severity with a CVSS score of 9.8. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

What to do next

Remediation and response

Microsoft Security Response Center guidance

Vendor revision: Jun 9, 2026

Vendor remediation details

To help protect against this vulnerability prior to installing the June 2026 security updates for your operating system, you may need to modify the MaxRequestBytes registry value used by the Windows HTTP stack if it isn't set to the default value. Note Systems using the default value (16384 bytes / 16 KB) are not impacted by this vulnerability. Configurations that increase this value beyond safe l Install KB5094123. Install KB5094128. Install KB5094127. Install KB5094125. Install KB5094126. Install KB5093998. Install KB5095051. Install KB5094122. Install KB5094042. Install KB5094041.

Vendor-listed releases

10.0.17763.8880
10.0.20348.5256
10.0.19044.7417
10.0.19045.7417
10.0.26100.32995
10.0.26200.8655
10.0.22631.7219
10.0.26100.8655
10.0.28000.2269
10.0.14393.9234
6.2.9200.26132
6.3.9600.23228

CISA KEVNot listedBased on the latest collected catalog

EPSS25.3%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-47291?

Integer overflow or wraparound in Windows HTTP.sys allows an unauthorized attacker to execute code over a network.

Source: NVD