CVE-2019-9514 — HTTP/2 Server Denial of Service Vulnerability

Executive Summary

A denial of service vulnerability exists in the HTTP/2 protocol stack (HTTP.sys) when HTTP.sys improperly parses specially crafted HTTP/2 requests. An attacker who successfully exploited the vulnerability could create a denial of service condition, causing the target system to become unresponsive. To exploit this vulnerability, an unauthenticated attacker could send a specially crafted HTTP packet to a target system, causing the affected system to become nonresponsive. The update addresses the vulnerability by modifying how the Windows HTTP protocol stack handles HTTP/2 requests. Note that the denial of service vulnerability would not allow an attacker to execute code or to elevate user rights.

Overview

7.5

CVSS HIGH

Important

MS Severity

Not Exploited

MS Exploit Status

Less Likely

MS Exploit Likelihood

Category Denial of Service

Released Aug 13 2019

Last Updated Aug 13 2019

Publicly Disclosed No

CISA KEV Not Listed

Known Exploits None Known

EPSS Score 0.82813 — 0.99628 percentile

CVSS Vector

ATTACK VECTOR

Network

ATTACK COMPLEXITY

Low

PRIVILEGES REQUIRED

None

USER INTERACTION

None

SCOPE

Unchanged

Temporal Score: 6.7

EPSS Score

0.82813

probability of exploitation in the next 30 days

0.99628 percentile - updated 2026-06-20

View on FIRST.org

Affected Products

25 affected products

Product	KB Article	Severity	Impact	Restart Required
Windows 10 for 32-bit Systems	`4512497 (Security Update)`	Important	Denial of Service	Yes
Windows 10 for x64-based Systems	`4512497 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1607 for 32-bit Systems	`4512517 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1607 for x64-based Systems	`4512517 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1703 for 32-bit Systems	`4512507 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1703 for x64-based Systems	`4512507 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1709 for 32-bit Systems	`4512516 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1709 for ARM64-based Systems	`4512516 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1709 for x64-based Systems	`4512516 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1803 for 32-bit Systems	`4512501 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1803 for ARM64-based Systems	`4512501 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1803 for x64-based Systems	`4512501 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1809 for 32-bit Systems	`4511553 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1809 for ARM64-based Systems	`4511553 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1809 for x64-based Systems	`4511553 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1903 for 32-bit Systems	`4512508 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1903 for ARM64-based Systems	`4512508 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1903 for x64-based Systems	`4512508 (Security Update)`	Important	Denial of Service	Yes
Windows Server 2016	`4512517 (Security Update)`	Important	Denial of Service	Yes
Windows Server 2016 (Server Core installation)	`4512517 (Security Update)`	Important	Denial of Service	Yes
Windows Server 2019	`4511553 (Security Update)`	Important	Denial of Service	Yes
Windows Server 2019 (Server Core installation)	`4511553 (Security Update)`	Important	Denial of Service	Yes
Windows Server, version 1709 (Server Core Installation)	`—`	Unknown	Unknown	Unknown
Windows Server, version 1803 (Server Core Installation)	`4512501 (Security Update)`	Important	Denial of Service	Yes
Windows Server, version 1903 (Server Core installation)	`4512508 (Security Update)`	Important	Denial of Service	Yes

Patches

8 patches

Article	Type	Restart
`4512497`	Security Update	Yes
`4512517`	Security Update	Yes
`4512507`	Security Update	Yes
`4512516`	Security Update	Yes
`4512501`	Security Update	Yes
`4511553`	Security Update	Yes
`4512508`	Security Update	Yes
`—`		Unknown

Known Exploits

No known exploits have been linked for this CVE yet. When available, exploit references will be sourced from public repositories and may be unverified, incomplete, or non-functional. Always review code carefully before use in any environment.

Acknowledgments

Jonathan Looney of Netflix

References

MSRC Advisory MITRE NVD