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Full vulnerability report · 2019
CVE-2019-0820High confidence

A denial of service vulnerability exists when .NET Framework and .NET Core improperly process RegEx strings, aka '.NET Framework and .NET Core Denial of Service Vulnerability'

Microsoft · Microsoft .NET Framework 4.5.2

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 5.72% 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 Microsoft .NET Framework 4.5.2 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 ranges1 source-attributed range

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
NuGetSystem.Text.RegularExpressionsECOSYSTEM: introduced 4.3.0; fixed 4.3.14.3.1OSV record ↗aggregator derived · 8 Nov 2023
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-2021-1682

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

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
Not supplied in the stored EUVD record
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 .NET Framework and .NET Core improperly process RegEx strings, aka '.NET Framework and .NET Core Denial of Service Vulnerability'. This CVE ID is unique from CVE-2019-0980, CVE-2019-0981.

What

A denial of service vulnerability exists when .NET Framework and .NET Core improperly process RegEx strings, aka '.NET Framework and .NET Core Denial of Service Vulnerability'. This CVE ID is unique from CVE-2019-0980, CVE-2019-0981.

Why

The product does not properly control the allocation and maintenance of a limited resource.

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 .NET Framework and .NET Core improperly process RegEx strings, aka '.NET Framework and .NET Core Denial of Service Vulnerability'. This CVE ID is unique from CVE-2019-0980, CVE-2019-0981.

Why

The product does not properly control the allocation and maintenance of a limited resource.

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 → Uncontrolled Resource Consumption → 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: a standard category for the underlying weakness.
CWE-400 ↗

CWE-400: Uncontrolled Resource Consumption. The product does not properly control the allocation and maintenance of a limited resource.

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 serviceCWE-400
A

Official authority intelligence

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

CERT-FR · French · CERTFR-2019-AVI-224Multiples vulnérabilités dans Microsoft .Net

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

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2019-003848.NET Framework および .NET Core におけるサービス運用妨害の脆弱性

.NET Framework および .NET Core には、RegEx strings 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「.NET Framework のサービス拒否の脆弱性」として公開しています。 本脆弱性は、CVE-2019-0980 および CVE-2019-0981 とは異なる脆弱性です。

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2019-003825Microsoft .NET Framework および .NET Core におけるサービス運用妨害 (DoS) にされる脆弱性

Microsoft .NET Framework および .NET Core には、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「.NET Framework と .NET Core のサービス拒否の脆弱性」として公開しています。 本脆弱性は、CVE-2019-0820 および CVE-2019-0980 とは異なる脆弱性です。

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2019-003824Microsoft .NET Framework および .NET Core におけるサービス運用妨害 (DoS) にされる脆弱性

Microsoft .NET Framework および .NET Core には、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「.NET Framework と .NET Core のサービス拒否の脆弱性」として公開しています。 本脆弱性は、CVE-2019-0820 および CVE-2019-0981 とは異なる脆弱性です。

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-5014MS 5월 보안 위협에 따른 정기 보안 업데이트 권고

##### □ 설명 o 이용자가 특수하게 제작된 악성 문서를 열람할 경우, 원격코드실행을 허용하는 취약점 o 관련취약점 : - 원격코드실행 취약점(CVE-2019-0952) - 권한상승 취약점(CVE-2019-0957,CVE-2019-0958) - 정보노출 취약점(CVE-2019-0956) - DID 취약점(CVE-2019-0949,CVE-2019-0950,CVE-2019-0951) o 영향 : 원격코드실행 o 중요도 : 중요 o 관련 KB번호 - 4464564, 4464549, 4464573, 4464556 ##### □ 해결책 o 영향 받는 소프트웨어를 이용하는 경우 마이크로소프트사의 보안 패치 적용 12. Skype 보안 업데이트 ##### □ 설명 o 공격자가 프로그램의 미흡한 설계(적절한 검증 부재)를 악용하여 제한된 자원에 접근가능한 정보노출 취약점 o 관련취약점 : - 정보노출 취약점(CVE-2019-0932) o 영향 : 정보노출 o 중요도 : 중요 ##### □ 해결책 o 영향 받는 소프트웨어를 이용하는 경우 마이크로소프트사의 보안 패치 적용 13. ASP.NET Core, .NET Core 보안 업데이트 ##### □ 설명 o 공격자가 시스템의 자원을 고갈시켜 발생하는 서비스거부 취약점 o 관련취약점 : - 서비스거부 취약점(CVE-2019-0820,CVE-2019-0864,CVE-2019-0980,CVE-2019-0981,CVE-2019-0982) o 영향 : 서비스거부 o 중요도 : 중요 o 관련 KB번호 - 4499409, 4498964, 4499167, 4499405, 4494440, 4499406, 4498961, 4499408, 4498963, 4499407, 4498962, 4495610, 4495611, 4495613, 4495616, 4495620, 4499154, 4499181, 4499179 ##### □ 해결책 o 영향 받는 소프트웨어를 이용하는 경우 마이크로소프트사의 보안 패치 적용 14. Team Foundation Server 보안 업데이트 ##### □ 설명 o 보안 강화 업데이트 o 관련취약점 : - 스푸핑 취약점(CVE-2019-0872) o 영향 : 스푸핑 o 중요도 : 중요 ##### □ 해결책 o 영향 받는 소프트웨어를 이용하는 경우 마이크로소프트사의 보안 패치 적용 15. Adobe Flash Player 보안 업데이트 ##### □ 설명 o 지원되는 모든 버전의 Windows 8.1, Windows Server 2012, Windows Server 2012 R2, Windows RT 8.1, Windows 10 및 Windows Server 2016

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
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.
Action
Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 16 May 2019 · Last source change 4 Aug 2024, 17:58 UTC · CWE-400 · Uncontrolled Resource Consumption

CVE recordCVE.org · 5.1
CVSS sourceNIST NVD
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-09-01
European sourceENISA EUVD · EUVD-2021-1682
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceNIST NVD
NVD statusNVD modified after enrichment

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. ENISA EUVD mappingEUVD-2021-1682 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2021-1682"}
    ENISA EUVD ↗
  2. Vendor guidanceAuthoritative vendor guidance changed: added patch: portal.msrc.microsoft.com/CVE-2019-0820; added remediation: portal.msrc.microsoft.com/CVE-2019-0820; removed vendor advisory: access.redhat.com/RHSA-2019:1259.
    Before
    vendor advisory: access.redhat.com/RHSA-2019:1259
    After
    patch: portal.msrc.microsoft.com/CVE-2019-0820 · remediation: portal.msrc.microsoft.com/CVE-2019-0820
    portal.msrc.microsoft.com ↗
  3. Affected versionsThe structured affected or fixed version information changed.
    Before
    Windows 7 for 32-bit Systems Service Pack 1; Windows 7 for x64-based Systems Service Pack 1; Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation); Windows Server 2008 R2 for x64-based Systems Service Pack 1; Windows Server 2012; Windows Server 2012 (Server Core installation); Windows 8.1 for 32-bit systems; Windows 8.1 for x64-based systems · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    Windows 7 for 32-bit Systems Service Pack 1; Windows 7 for x64-based Systems Service Pack 1; Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation); Windows Server 2008 R2 for x64-based Systems Service Pack 1; Windows Server 2012; Windows Server 2012 (Server Core installation); Windows 8.1 for 32-bit systems; Windows 8.1 for x64-based systems · 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 ↗
  4. Remediation statusRemediation status changed from Awaiting fix to Patch available.
    Before
    Awaiting fix
    After
    Patch available
    portal.msrc.microsoft.com ↗
  5. SeveritySeverity changed from Unknown to High.
    Before
    Unknown
    After
    High
    NIST NVD ↗
  6. CVSS scoreCVSS score changed from not recorded to 7.5 (CVSS 3.1 · NIST NVD · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).
    Before
    not recorded
    After
    7.5 (CVSS 3.1 · NIST NVD · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
    NIST NVD ↗
  7. Catalogue recordCVE added to the BlackTree catalogue.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2021-1682↗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-2019-0820 · cve.blacktree.nl