CVE-2019-0820 — .NET Framework and .NET Core Denial of Service Vulnerability

Important CVSS 7.5 EPSS 0.05719 2019-05 archive

Executive Summary

A denial of service vulnerability exists when .NET Framework and .NET Core improperly process RegEx strings. An attacker who successfully exploited this vulnerability could cause a denial of service against a .NET application. A remote unauthenticated attacker could exploit this vulnerability by issuing specially crafted requests to a .NET Framework (or .NET core) application. The update addresses the vulnerability by correcting how .NET Framework and .NET Core applications handle RegEx string processing.

Overview

7.5

CVSS HIGH

Important

MS Severity

Not Exploited

MS Exploit Status

Less Likely

MS Exploit Likelihood

Category Denial of Service

Released May 14 2019

Last Updated May 14 2019

Publicly Disclosed No

CISA KEV Not Listed

Known Exploits None Known

EPSS Score 0.05719 — 0.92216 percentile

NVD CVSS 7.5 HIGH — differs from MSRC

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

ATTACK VECTOR

Network

ATTACK COMPLEXITY

Low

PRIVILEGES REQUIRED

None

USER INTERACTION

None

SCOPE

Unchanged

EPSS Score

0.05719

probability of exploitation in the next 30 days

0.92216 percentile - updated 2026-07-25

View on FIRST.org

Affected Products

57 affected products

Product	KB Article	Severity	Impact	Restart Required
.NET Core 1.0	`Release Notes (Security Update)`	Important	Denial of Service	Maybe
.NET Core 1.1	`Release Notes (Security Update)`	Important	Denial of Service	Maybe
.NET Core 2.1	`Release Notes (Security Update)`	Important	Denial of Service	Maybe
.NET Core 2.2	`Release Notes (Security Update)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 2.0 Service Pack 2 on Windows Server 2008 for 32-bit Systems Service Pack 2 4499409 (Monthly Rollup) 4498964 (Security Only) Important Denial of Service 4487081; 4487259 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 2.0 Service Pack 2 on Windows Server 2008 for Itanium-Based Systems Service Pack 2 4499409 (Monthly Rollup) 4498964 (Security Only) Important Denial of Service 4487081; 4487259 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 2.0 Service Pack 2 on Windows Server 2008 for x64-based Systems Service Pack 2 4499409 (Monthly Rollup) 4498964 (Security Only) Important Denial of Service 4487081; 4487259 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 3.0 Service Pack 2 on Windows Server 2008 for 32-bit Systems Service Pack 2 4499409 (Monthly Rollup) 4498964 (Security Only) Important Denial of Service 4487081; 4487259 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 3.0 Service Pack 2 on Windows Server 2008 for Itanium-Based Systems Service Pack 2 4499409 (Monthly Rollup) 4498964 (Security Only) Important Denial of Service 4487081; 4487259 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 3.0 Service Pack 2 on Windows Server 2008 for x64-based Systems Service Pack 2 4499409 (Monthly Rollup) 4498964 (Security Only) Important Denial of Service 4487081; 4487259 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 3.5 on Windows 10 for 32-bit Systems	`4499154 (Security Update)`	Important	Denial of Service	Yes
Microsoft .NET Framework 3.5 on Windows 10 for x64-based Systems	`4499154 (Security Update)`	Important	Denial of Service	Yes
Microsoft .NET Framework 3.5 on Windows 10 Version 1607 for 32-bit Systems	`4494440 (Security Update)`	Important	Denial of Service	Yes
Microsoft .NET Framework 3.5 on Windows 10 Version 1607 for x64-based Systems	`4494440 (Security Update)`	Important	Denial of Service	Yes
Microsoft .NET Framework 3.5 on Windows 10 Version 1703 for 32-bit Systems	`4499181 (Security Update)`	Important	Denial of Service	Yes
Microsoft .NET Framework 3.5 on Windows 10 Version 1703 for x64-based Systems	`4499181 (Security Update)`	Important	Denial of Service	Yes
Microsoft .NET Framework 3.5 on Windows 10 Version 1709 for 32-bit Systems	`4499179 (Security Update)`	Important	Denial of Service	Yes
Microsoft .NET Framework 3.5 on Windows 10 Version 1709 for ARM64-based Systems	`4499179 (Security Update)`	Important	Denial of Service	Yes
Microsoft .NET Framework 3.5 on Windows 10 Version 1709 for x64-based Systems	`4499179 (Security Update)`	Important	Denial of Service	Yes
Microsoft .NET Framework 3.5 on Windows 10 Version 1803 for 32-bit Systems	`4499167 (Security Update)`	Important	Denial of Service	Yes
Microsoft .NET Framework 3.5 on Windows 10 Version 1803 for ARM64-based Systems	`4499167 (Security Update)`	Important	Denial of Service	Yes
Microsoft .NET Framework 3.5 on Windows 10 Version 1803 for x64-based Systems	`4499167 (Security Update)`	Important	Denial of Service	Yes
Microsoft .NET Framework 3.5 on Windows 10 Version 1809 for 32-bit Systems	`4499405 (Security Update)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 3.5 on Windows 10 Version 1809 for x64-based Systems	`4499405 (Security Update)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 3.5 on Windows 10 Version 1903 for 32-bit Systems	`4495620 (Security Update)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 3.5 on Windows 10 Version 1903 for x64-based Systems	`4495620 (Security Update)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 3.5 on Windows 8.1 for 32-bit systems 4499408 (Monthly Rollup) 4498963 (Security Only) Important Denial of Service 4489488; 4495165 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 3.5 on Windows 8.1 for x64-based systems 4499408 (Monthly Rollup) 4498963 (Security Only) Important Denial of Service 4489488; 4495165 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 3.5 on Windows Server 2012 4499407 (Monthly Rollup) 4498962 (Security Only) Important Denial of Service 4487079; 4487257 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 3.5 on Windows Server 2012 (Server Core installation) 4499407 (Monthly Rollup) 4498962 (Security Only) Important Denial of Service 4487079; 4487257 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 3.5 on Windows Server 2012 R2 4499408 (Monthly Rollup) 4498963 (Security Only) Important Denial of Service 4489488; 4495165 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 3.5 on Windows Server 2012 R2 (Server Core installation) 4499408 (Monthly Rollup) 4498963 (Security Only) Important Denial of Service 4489488; 4495165 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 3.5 on Windows Server 2016	`4494440 (Security Update)`	Important	Denial of Service	Yes
Microsoft .NET Framework 3.5 on Windows Server 2016 (Server Core installation)	`4494440 (Security Update)`	Important	Denial of Service	Yes
Microsoft .NET Framework 3.5 on Windows Server 2019	`4499405 (Security Update)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 3.5 on Windows Server 2019 (Server Core installation)	`4499405 (Security Update)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 3.5 on Windows Server, version 1803 (Server Core Installation)	`4499167 (Security Update)`	Important	Denial of Service	Yes
Microsoft .NET Framework 3.5 on Windows Server, version 1903 (Server Core installation)	`4495620 (Security Update)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 3.5.1 on Windows 7 for 32-bit Systems Service Pack 1 4499406 (Monthly Rollup) 4498961 (Security Only) Important Denial of Service 4487078; 4487256 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 3.5.1 on Windows 7 for x64-based Systems Service Pack 1 4499406 (Monthly Rollup) 4498961 (Security Only) Important Denial of Service 4487078; 4487256 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 3.5.1 on Windows Server 2008 R2 for Itanium-Based Systems Service Pack 1 4499406 (Monthly Rollup) 4498961 (Security Only) Important Denial of Service 4487078; 4487256 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 3.5.1 on Windows Server 2008 R2 for x64-based Systems Service Pack 1 4499406 (Monthly Rollup) 4498961 (Security Only) Important Denial of Service 4487078; 4487256 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 3.5.1 on Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation) 4499406 (Monthly Rollup) 4498961 (Security Only) Important Denial of Service 4487078; 4487256 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.5.2 on Windows 7 for 32-bit Systems Service Pack 1 4499406 (Monthly Rollup) 4498961 (Security Only) Important Denial of Service Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.5.2 on Windows 7 for x64-based Systems Service Pack 1 4499406 (Monthly Rollup) 4498961 (Security Only) Important Denial of Service Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.5.2 on Windows 8.1 for 32-bit systems 4499408 (Monthly Rollup) 4498963 (Security Only) Important Denial of Service 4489488; 4495165 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.5.2 on Windows 8.1 for x64-based systems 4499408 (Monthly Rollup) 4498963 (Security Only) Important Denial of Service 4489488; 4495165 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.5.2 on Windows RT 8.1	`4499408 (Monthly Rollup)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 4.5.2 on Windows Server 2008 for 32-bit Systems Service Pack 2 4499409 (Monthly Rollup) 4498964 (Security Only) Important Denial of Service 4487081; 4487259 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.5.2 on Windows Server 2008 for x64-based Systems Service Pack 2 4499409 (Monthly Rollup) 4498964 (Security Only) Important Denial of Service 4487081; 4487259 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.5.2 on Windows Server 2008 R2 for x64-based Systems Service Pack 1 4499406 (Monthly Rollup) 4498961 (Security Only) Important Denial of Service Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.5.2 on Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation) 4499406 (Monthly Rollup) 4498961 (Security Only) Important Denial of Service Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.5.2 on Windows Server 2012 4499407 (Monthly Rollup) 4498962 (Security Only) Important Denial of Service 4487079; 4487257 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.5.2 on Windows Server 2012 (Server Core installation) 4499407 (Monthly Rollup) 4498962 (Security Only) Important Denial of Service 4487079; 4487257 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.5.2 on Windows Server 2012 R2 4499408 (Monthly Rollup) 4498963 (Security Only) Important Denial of Service 4489488; 4495165 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.5.2 on Windows Server 2012 R2 (Server Core installation) 4499408 (Monthly Rollup) 4498963 (Security Only) Important Denial of Service 4489488; 4495165 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.6 on Windows Server 2008 for 32-bit Systems Service Pack 2 4499409 (Monthly Rollup) 4498964 (Security Only) Important Denial of Service 4487081; 4487259 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.6 on Windows Server 2008 for x64-based Systems Service Pack 2 4499409 (Monthly Rollup) 4498964 (Security Only) Important Denial of Service 4487081; 4487259 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2016	`4494440 (Security Update)`	Important	Denial of Service	Yes
Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2016 (Server Core installation)	`4494440 (Security Update)`	Important	Denial of Service	Yes
Microsoft .NET Framework 4.6/4.6.1/4.6.2/4.7/4.7.1/4.7.2 on Windows 7 for 32-bit Systems Service Pack 1 4499406 (Monthly Rollup) 4498961 (Security Only) Important Denial of Service Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.6/4.6.1/4.6.2/4.7/4.7.1/4.7.2 on Windows 7 for x64-based Systems Service Pack 1 4499406 (Monthly Rollup) 4498961 (Security Only) Important Denial of Service Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.6/4.6.1/4.6.2/4.7/4.7.1/4.7.2 on Windows 8.1 for 32-bit systems 4499408 (Monthly Rollup) 4498963 (Security Only) Important Denial of Service 4489488; 4495165 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.6/4.6.1/4.6.2/4.7/4.7.1/4.7.2 on Windows 8.1 for x64-based systems 4499408 (Monthly Rollup) 4498963 (Security Only) Important Denial of Service 4489488; 4495165 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.6/4.6.1/4.6.2/4.7/4.7.1/4.7.2 on Windows RT 8.1	`4499408 (Monthly Rollup)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 4.6/4.6.1/4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2008 R2 for x64-based Systems Service Pack 1 4499406 (Monthly Rollup) 4498961 (Security Only) Important Denial of Service Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.6/4.6.1/4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation) 4499406 (Monthly Rollup) 4498961 (Security Only) Important Denial of Service Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.6/4.6.1/4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2012 4499407 (Monthly Rollup) 4498962 (Security Only) Important Denial of Service 4487079; 4487257 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.6/4.6.1/4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2012 (Server Core installation) 4499407 (Monthly Rollup) 4498962 (Security Only) Important Denial of Service 4487079; 4487257 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.6/4.6.1/4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2012 R2 4499408 (Monthly Rollup) 4498963 (Security Only) Important Denial of Service 4489488; 4495165 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.6/4.6.1/4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2012 R2 (Server Core installation) 4499408 (Monthly Rollup) 4498963 (Security Only) Important Denial of Service 4489488; 4495165 Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.7.2 on Windows 10 Version 1803 for 32-bit Systems	`4499167 (Security Update)`	Important	Denial of Service	Yes
Microsoft .NET Framework 4.7.2 on Windows 10 Version 1803 for ARM64-based Systems	`4499167 (Security Update)`	Important	Denial of Service	Yes
Microsoft .NET Framework 4.7.2 on Windows 10 Version 1803 for x64-based Systems	`4499167 (Security Update)`	Important	Denial of Service	Yes
Microsoft .NET Framework 4.7.2 on Windows Server 2019	`4499405 (Security Update)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 4.7.2 on Windows Server 2019 (Server Core installation)	`4499405 (Security Update)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 4.7.2 on Windows Server, version 1803 (Server Core Installation)	`4499167 (Security Update)`	Important	Denial of Service	Yes
Microsoft .NET Framework 4.8 on Windows 10 Version 1607 for 32-bit Systems	`4495610 (Security Update)`	Important	Denial of Service	Unknown
Microsoft .NET Framework 4.8 on Windows 10 Version 1607 for x64-based Systems	`4495610 (Security Update)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 4.8 on Windows 10 Version 1703 for 32-bit Systems	`4495611 (Security Update)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 4.8 on Windows 10 Version 1703 for x64-based Systems	`4495611 (Security Update)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 4.8 on Windows 10 Version 1709 for 32-bit Systems	`4495613 (Security Update)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 4.8 on Windows 10 Version 1709 for x64-based Systems	`4495613 (Security Update)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 4.8 on Windows 10 Version 1803 for 32-bit Systems	`4495616 (Security Update)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 4.8 on Windows 10 Version 1803 for x64-based Systems	`4495616 (Security Update)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 4.8 on Windows 10 Version 1809 for 32-bit Systems	`4499405 (Security Update)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 4.8 on Windows 10 Version 1809 for x64-based Systems	`4499405 (Security Update)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 4.8 on Windows 10 Version 1903 for 32-bit Systems	`4495620 (Security Update)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 4.8 on Windows 10 Version 1903 for x64-based Systems	`4495620 (Security Update)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 4.8 on Windows 7 for 32-bit Systems Service Pack 1 4499406 (Monthly Rollup) 4498961 (Security Only) Important Denial of Service Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.8 on Windows 7 for x64-based Systems Service Pack 1 4499406 (Monthly Rollup) 4498961 (Security Only) Important Denial of Service Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.8 on Windows 8.1 for 32-bit systems 4499408 (Monthly Rollup) 4498963 (Security Only) Important Denial of Service Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.8 on Windows 8.1 for x64-based systems 4499408 (Monthly Rollup) 4498963 (Security Only) Important Denial of Service Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.8 on Windows RT 8.1	`4499408 (Monthly Rollup)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 4.8 on Windows Server 2008 R2 for x64-based Systems Service Pack 1 4499406 (Monthly Rollup) 4498961 (Security Only) Important Denial of Service Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.8 on Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation) 4499406 (Monthly Rollup) 4498961 (Security Only) Important Denial of Service Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.8 on Windows Server 2012 4499407 (Monthly Rollup) 4498962 (Security Only) Important Denial of Service Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.8 on Windows Server 2012 (Server Core installation) 4499407 (Monthly Rollup) 4498962 (Security Only) Important Denial of Service Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.8 on Windows Server 2012 R2 4499408 (Monthly Rollup) 4498963 (Security Only) Important Denial of Service Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.8 on Windows Server 2012 R2 (Server Core installation) 4499408 (Monthly Rollup) 4498963 (Security Only) Important Denial of Service Base: N/A Temporal: N/A Vector: N/A Maybe None Microsoft .NET Framework 4.8 on Windows Server 2016	`4495610 (Security Update)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 4.8 on Windows Server 2016 (Server Core installation)	`4495610 (Security Update)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 4.8 on Windows Server 2019	`4499405 (Security Update)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 4.8 on Windows Server 2019 (Server Core installation)	`4499405 (Security Update)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 4.8 on Windows Server, version 1803 (Server Core Installation)	`4495616 (Security Update)`	Important	Denial of Service	Maybe
Microsoft .NET Framework 4.8 on Windows Server, version 1903 (Server Core installation)	`4495620 (Security Update)`	Important	Denial of Service	Maybe
PowerShell Core 6.1	`Release Notes (Security Update)`	Important	Denial of Service	Maybe
PowerShell Core 6.2	`Release Notes (Security Update)`	Important	Denial of Service	Maybe

Patches

13 patches

Article	Type	Restart
`Release Notes`	Security Update	Maybe
`4499154`	Security Update	Yes
`4494440`	Security Update	Yes
`4499181`	Security Update	Yes
`4499179`	Security Update	Yes
`4499167`	Security Update	Yes
`4499405`	Security Update	Maybe
`4495620`	Security Update	Maybe
`4499408`	Monthly Rollup	Maybe
`4495610`	Security Update	Unknown
`4495611`	Security Update	Maybe
`4495613`	Security Update	Maybe
`4495616`	Security Update	Maybe

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

None

References

MSRC Advisory MITRE NVD

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