CVE-2026-47291: HTTP.sys Remote Code Execution Vulnerability

criticalCVSS 9.8CVE-2026-47291

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

CSIRTS triage

vendor: Microsoft product: Windows HTTP.sys Remote code execution

What: Integer overflow or wraparound allows an unauthorized attacker to execute code over a network.
Who is affected: All deployments of Windows HTTP.sys.
Urgency: Remediation is critical due to high severity and potential for remote code execution.
Action: Apply the latest security updates from Microsoft.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: critical — CVSS 9.8
Published: 2026-06-09
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-47291

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Elevated exploitation riskCVE-2026-4729121.5% 30-day exploitation probability — well above the norm. Schedule remediation this cycle. Riskier than 97% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-47291	coverage & exploitation status	NVD · CVE.org

Recent advisories for HTTP.sys Remote Code

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

criticalexploitedCVE-2015-1635: Microsoft HTTP.sys Remote Code Execution Vulnerabilitycisa-kev · 2022-02-10