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Full vulnerability report · 2020
CVE-2020-1161High confidence

ASP.NET Core Denial of Service Vulnerability

Microsoft · ASP.NET Core 3.1

7.5HighCVSS 3.1
Recommended action
Within 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityHighOperational priority:High, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 5.14% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs Microsoft ASP.NET Core 3.1 and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 30 daysRemediation target: Within 180 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Open-source package ranges9 source-attributed ranges

These OSV and GitHub advisory ranges apply only to the named package and ecosystem. A listed fixed version is not a universal product patch or proof that an update is installed.

Ecosystem and packageAffected rangeFirst fixed versionEvidence
NuGetMicrosoft.AspNetCore.App.Runtime.linux-armECOSYSTEM: introduced 3.1.0; fixed 3.1.43.1.4OSV record ↗aggregator derived · 6 Dec 2023
NuGetMicrosoft.AspNetCore.App.Runtime.linux-arm64ECOSYSTEM: introduced 3.1.0; fixed 3.1.43.1.4OSV record ↗aggregator derived · 6 Dec 2023
NuGetMicrosoft.AspNetCore.App.Runtime.linux-musl-arm64ECOSYSTEM: introduced 3.1.0; fixed 3.1.43.1.4OSV record ↗aggregator derived · 6 Dec 2023
NuGetMicrosoft.AspNetCore.App.Runtime.linux-musl-x64ECOSYSTEM: introduced 3.1.0; fixed 3.1.43.1.4OSV record ↗aggregator derived · 6 Dec 2023
NuGetMicrosoft.AspNetCore.App.Runtime.linux-x64ECOSYSTEM: introduced 3.1.0; fixed 3.1.43.1.4OSV record ↗aggregator derived · 6 Dec 2023
NuGetMicrosoft.AspNetCore.App.Runtime.osx-x64ECOSYSTEM: introduced 3.1.0; fixed 3.1.43.1.4OSV record ↗aggregator derived · 6 Dec 2023
NuGetMicrosoft.AspNetCore.App.Runtime.win-armECOSYSTEM: introduced 3.1.0; fixed 3.1.43.1.4OSV record ↗aggregator derived · 6 Dec 2023
NuGetMicrosoft.AspNetCore.App.Runtime.win-x64ECOSYSTEM: introduced 3.1.0; fixed 3.1.43.1.4OSV record ↗aggregator derived · 6 Dec 2023
NuGetMicrosoft.AspNetCore.App.Runtime.win-x86ECOSYSTEM: introduced 3.1.0; fixed 3.1.43.1.4OSV record ↗aggregator derived · 6 Dec 2023
Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current
CVE-2020-1161 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitydotnet: Denial of service due to infinite loop
58 fixed

The vendor explicitly identifies these products or versions as containing the fix.

  • rh-dotnet31-aspnetcore-runtime-3.1-0:3.1.4-2.el7.x86_64 as a component of .NET Core on Red Hat Enterprise Linux ComputeNode (v. 7)
  • rh-dotnet31-aspnetcore-targeting-pack-3.1-0:3.1.4-2.el7.x86_64 as a component of .NET Core on Red Hat Enterprise Linux ComputeNode (v. 7)
  • rh-dotnet31-dotnet-0:3.1.104-2.el7.src as a component of .NET Core on Red Hat Enterprise Linux ComputeNode (v. 7)
  • rh-dotnet31-dotnet-0:3.1.104-2.el7.x86_64 as a component of .NET Core on Red Hat Enterprise Linux ComputeNode (v. 7)
  • rh-dotnet31-dotnet-apphost-pack-3.1-0:3.1.4-2.el7.x86_64 as a component of .NET Core on Red Hat Enterprise Linux ComputeNode (v. 7)
  • rh-dotnet31-dotnet-debuginfo-0:3.1.104-2.el7.x86_64 as a component of .NET Core on Red Hat Enterprise Linux ComputeNode (v. 7)
  • rh-dotnet31-dotnet-host-0:3.1.4-2.el7.x86_64 as a component of .NET Core on Red Hat Enterprise Linux ComputeNode (v. 7)
  • rh-dotnet31-dotnet-hostfxr-3.1-0:3.1.4-2.el7.x86_64 as a component of .NET Core on Red Hat Enterprise Linux ComputeNode (v. 7)
  • rh-dotnet31-dotnet-runtime-3.1-0:3.1.4-2.el7.x86_64 as a component of .NET Core on Red Hat Enterprise Linux ComputeNode (v. 7)
  • rh-dotnet31-dotnet-sdk-3.1-0:3.1.104-2.el7.x86_64 as a component of .NET Core on Red Hat Enterprise Linux ComputeNode (v. 7)
  • rh-dotnet31-dotnet-targeting-pack-3.1-0:3.1.4-2.el7.x86_64 as a component of .NET Core on Red Hat Enterprise Linux ComputeNode (v. 7)
  • rh-dotnet31-dotnet-templates-3.1-0:3.1.104-2.el7.x86_64 as a component of .NET Core on Red Hat Enterprise Linux ComputeNode (v. 7)
Summary
An infinite loop was found in the HTTP Routing component of Microsoft.AspNetCore.App, which could be exploited by a remote, unauthenticated attacker. This flaw allows an attacker without special privileges to send crafted requests to a machine running an ASP.NET Core application, triggering the infinite loop and causing a denial of service in that application, for example, a web server.
Remediation
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2022-2160

No EUVD known-exploited evidence

A denial of service vulnerability exists when ASP.NET Core improperly handles web requests. An attacker who successfully exploited this vulnerability could cause a denial of service against an ASP.NET Core web application. The vulnerability can be exploited remotely, without authentication. A remote unauthenticated attacker could exploit this vulnerability by issuing specially crafted requests to the ASP.NET Core application. The update addresses the vulnerability by correcting how the ASP.NET Core web application handles web requests.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
0.0
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

A denial of service vulnerability exists when ASP.NET Core improperly handles web requests. An attacker who successfully exploited this vulnerability could cause a denial of service against an ASP.NET Core web application. The vulnerability can be exploited remotely, without authentication. A remote unauthenticated attacker could exploit this vulnerability by issuing specially crafted requests to the ASP.NET Core application. The update addresses the vulnerability by correcting how the ASP.NET Core web application handles web requests.

What

A denial of service vulnerability exists when ASP.NET Core improperly handles web requests. An attacker who successfully exploited this vulnerability could cause a denial of service against an ASP.NET Core web application. The vulnerability can be exploited remotely, without authentication. A remote unauthenticated attacker could exploit this vulnerability by issuing specially crafted requests to the ASP.NET Core application. The update addresses the vulnerability by correcting how the ASP.NET Core web application handles web requests.

Why

The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.

What

A denial of service vulnerability exists when ASP.NET Core improperly handles web requests. An attacker who successfully exploited this vulnerability could cause a denial of service against an ASP.NET Core web application. The vulnerability can be exploited remotely, without authentication. A remote unauthenticated attacker could exploit this vulnerability by issuing specially crafted requests to the ASP.NET Core application. The update addresses the vulnerability by correcting how the ASP.NET Core web application handles web requests.

Why

The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → vulnerable operation → disrupt the affected service
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration.
CWE not yet assigned
CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CNoneConfidentiality impact: No direct loss is represented by this metric.INoneIntegrity impact: No direct loss is represented by this metric.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedDenial of service
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2022-2160Official EUVD mapping

A denial of service vulnerability exists when ASP.NET Core improperly handles web requests. An attacker who successfully exploited this vulnerability could cause a denial of service against an ASP.NET Core web application. The vulnerability can be exploited remotely, without authentication. A remote unauthenticated attacker could exploit this vulnerability by issuing specially crafted requests to the ASP.NET Core application. The update addresses the vulnerability by correcting how the ASP.NET Core web application handles web requests.

Official EUVD record ↗
Cyber Security Agency of Singapore · English · CSA-SB-20200527Security Bulletin 27 May 2020

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 27 May 2020, published on 27 May 2020. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2020-AVI-289Multiples vulnérabilités dans les produits Microsoft

De multiples vulnérabilités ont été corrigées dans les produits Microsoft . Elles permettent à un attaquant de provoquer un déni de service, une exécution de code à distance et une usurpation d'identité.

Official advisory ↗
CERT-FR · French · CERTFR-2020-AVI-288Multiples vulnérabilités dans Microsoft .Net

De multiples vulnérabilités ont été corrigées dans Microsoft .Net . Elles permettent à un attaquant de provoquer un déni de service et une élévation de privilèges.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2020-005783ASP.NET Core および Microsoft Visual Studio におけるサービス運用妨害 (DoS) の脆弱性

ASP.NET Core および Microsoft Visual Studio には、ASP.NET Core が Web リクエストを適切に処理しない場合、サービス運用妨害 (DoS) の脆弱性が存在します。 ベンダは、本脆弱性を「ASP.NET Core のサービス拒否の脆弱性」として公開しています。

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-5139MS 5월 보안 위협에 따른 정기 보안 업데이트 권고

E-2020-1102) - 정보노출 취약점(CVE-2020-1103) - 스푸핑(CVE-2020-1099, CVE-2020-1100, CVE-2020-1101, CVE-2020-1104, CVE-2020-1105, CVE-2020-1106, CVE-2020-1107) o 영향 : 원격코드실행 o 중요도 : 긴급 o 관련 KB번호 - 4484332, 4484336, 4484352, 4484364, 4484383 ##### □ 해결책 o 영향 받는 소프트웨어를 이용하는 경우 마이크로소프트사의 보안 패치 적용 7. Microsoft Dynamics 관련 소프트웨어 보안 업데이트 ##### □ 설명 o 공격자가 특수하게 제작된 악성 응용 프로그램을 실행할 경우 발생하는 스푸핑 취약점 o 관련취약점 : - 스푸핑(CVE-2020-1063, ) o 영향 : 스푸핑 o 중요도 : 중요 o 관련 KB번호 - 4552002, 4551998 ##### □ 해결책 o 영향 받는 소프트웨어를 이용하는 경우 마이크로소프트사의 보안 패치 적용 8. .NET Framework 관련 소프트웨어 보안 업데이트 ##### □ 설명 o 공격자가 특수하게 제작된 악성 응용 프로그램을 실행할 경우 발생하는 권한상승 취약점 o 관련취약점 : - 서비스 거부(CVE-2020-1108, CVE-2020-1161) - 권한상승(CVE-2020-1066) o 영향 : 권한상승 o 중요도 : 중요 o 관련 KB번호 - 4552926, 4552928, 4552929, 4552931, 4556399, 4556400, 4556401, 4556402, 4556403, 4556404, 4556405, 4556406, 4556441, 4556807, 4556812, 4556813, 4556826 ##### □ 해결책 o 영향 받는 소프트웨어를 이용하는 경우 마이크로소프트사의 보안 패치 적용 9. Visual Studio 보안 업데이트 ##### □ 설명 o 공격자가 특수하게 제작된 악성 응용 프로그램을 실행할 경우 발생하는 원격코드 취약점 o 관련취약점 : - 서비스 거부(CVE-2020-1108, CVE-2020-1161) - 원격코드 실행(CVE-2020-1171, CVE-2020-1192) o 영향 : 원격코드 실행 o 중요도 : 긴급 ##### □ 해결책 o 영향 받는 소프트웨어를 이용하는 경우 마이크로소프트사의 보안 패치 적용 10. ChakraCore 보안 업데이트 ##### □ 설명 o 공격자가 특수하게 제작된 악성 응용 프로그램을 실행할 경우 발생하는 원격코드 취약점 o 관련취약점 : - 원격코드 실행(CVE-2020-1065, CVE-2020-1037

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
Fixed
Action
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258
Workaround
No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04

Evidence and provenance

Published 21 May 2020 · Last source change 19 Aug 2026, 16:34 UTC · CWE not yet assigned

CVE recordCVE.org · 5.2
CVSS sourceNIST NVD
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2022-2160
Product sourceCNA
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceUnavailable
NVD statusNVD modified after enrichment

Missing structured fields: CWE classification. Missing data is not evidence of low risk; review the primary advisory.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    3.0 < publication; 15.9.0 < publication; 16.0 < publication · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    After
    3.0 < publication; 15.9.0 < publication; 16.0 < publication · Fixed: For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258
    Red Hat Product Security ↗
  2. Vendor guidanceAuthoritative vendor guidance changed: added remediation: portal.msrc.microsoft.com/CVE-2020-1161; removed patch: msrc.microsoft.com/CVE-2020-1161; removed remediation: msrc.microsoft.com/CVE-2020-1161.
    Before
    patch: msrc.microsoft.com/CVE-2020-1161 · patch: portal.msrc.microsoft.com/CVE-2020-1161 · remediation: msrc.microsoft.com/CVE-2020-1161
    After
    patch: portal.msrc.microsoft.com/CVE-2020-1161 · remediation: portal.msrc.microsoft.com/CVE-2020-1161
    portal.msrc.microsoft.com ↗
  3. Vendor guidanceAuthoritative vendor guidance changed: added patch: msrc.microsoft.com/CVE-2020-1161; added remediation: msrc.microsoft.com/CVE-2020-1161; removed remediation: portal.msrc.microsoft.com/CVE-2020-1161.
    Before
    patch: portal.msrc.microsoft.com/CVE-2020-1161 · remediation: portal.msrc.microsoft.com/CVE-2020-1161
    After
    patch: msrc.microsoft.com/CVE-2020-1161 · patch: portal.msrc.microsoft.com/CVE-2020-1161 · remediation: msrc.microsoft.com/CVE-2020-1161
    msrc.microsoft.com ↗
  4. Affected versionsThe structured affected or fixed version information changed.
    Before
    unspecified; 16.0; 3.1 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    After
    3.0 < publication; 15.9.0 < publication; 16.0 < publication · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
Fixed release recorded from official guidance
ENISA EUVD · EUVD-2022-2160↗Red Hat Product Security security advisory↗Patch or update reference↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2020-1161 · cve.blacktree.nl