Summary
Impact: Remote Code Execution. Microsoft rating: Critical. Not known to be exploited — Exploitation More Likely. Customer action: Required.
Details
How could an attacker exploit this vulnerability?
In most situations, an unauthenticated attacker could send a specially crafted packet to a targeted server utilizing the HTTP Protocol Stack (http.sys) to process packets.
Security updates
10.0.17763.8880 — https://support.microsoft.com/help/5094123
10.0.20348.5256 — https://support.microsoft.com/help/5094128
10.0.19044.7417 — https://support.microsoft.com/help/5094127
10.0.26100.32995 — https://support.microsoft.com/help/5094125
10.0.26200.8655 — https://support.microsoft.com/help/5094126
10.0.22631.7219 — https://support.microsoft.com/help/5093998
10.0.28000.2269 — https://support.microsoft.com/help/5095051
10.0.14393.9234 — https://support.microsoft.com/help/5094122
6.2.9200.26132 — https://support.microsoft.com/help/5094042
6.3.9600.23228 — https://support.microsoft.com/help/5094041
Vulnerabilities 1
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Critical 9.8CVE-2026-47291 EPSS 25%
HTTP.sys Remote Code Execution Vulnerability
Integer overflow or wraparound in Windows HTTP.sys allows an unauthorized attacker to execute code over a network.
Revision history
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#1
Information published.
References
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CVE-2026-47291 HTTP.sys Remote Code Execution Vulnerability - HTML
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-47291
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Microsoft Exploitability Index
https://www.microsoft.com/en-us/msrc/exploitability-index?rtc=1
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Microsoft Support Lifecycle
https://support.microsoft.com/lifecycle
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Common Vulnerability Scoring System
https://www.first.org/cvss