What is CVE-2019-0820?

CVE-2019-0820 is a high-severity vulnerability in Microsoft .Net Framework 2.0, classified under Uncontrolled Resource Consumption. CVSS score: 7.5/10. Published 2019-05-16.

How severe is CVE-2019-0820?

High severity. CVSS v3 base score is 7.5 out of 10.

Is CVE-2019-0820 known to be exploited?

6 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Resource exhaustion in Microsoft .Net Framework 2.0

CVE-2019-0820

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.

Vulnerability class: DoS (Denial of Service)

Published 2019-05-16 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.057 (93.0th percentile), scored 2026-10-20.

Low probability of exploitation in the next 30 days, but still tracked. 93rd percentile — 93.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.057 · newest: 0.057 · change: 0.000

Affected products

Microsoft .Net Framework 2.0 — versions Service Pack 2 on Windows Server 2008 for Itanium-Based Systems Service Pack 2, Service Pack 2 on Windows Server 2008 for 32-bit Systems Service Pack 2, Service Pack 2 on Windows Server 2008 for x64-based Systems Service Pack 2
Microsoft .Net Framework 3.0 — versions Service Pack 2 on Windows Server 2008 for Itanium-Based Systems Service Pack 2, Service Pack 2 on Windows Server 2008 for 32-bit Systems Service Pack 2, Service Pack 2 on Windows Server 2008 for x64-based Systems Service Pack 2
Microsoft .Net Framework 3.5 — versions Windows Server 2012, Windows Server 2012 (Server Core installation), Windows 8.1 for 32-bit systems
Microsoft .Net Framework 3.5.1 — versions 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)
Microsoft .Net Framework 3.5 On Windows 10 Version 1903 For 32-Bit Systems — versions unspecified
Microsoft .Net Framework 3.5 On Windows 10 Version 1903 For X64-Based Systems — versions unspecified
Microsoft .Net Framework 3.5 On Windows Server, Version 1903 (Server Core Installation) — versions unspecified
Microsoft .Net Framework 4.5.2 — versions 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)
Microsoft .Net Framework 4.6 — versions Windows Server 2008 for 32-bit Systems Service Pack 2, Windows Server 2008 for x64-based Systems Service Pack 2
Microsoft .Net Framework 4.6.2/4.7/4.7.1/4.7.2 — versions Windows Server 2016, Windows Server 2016 (Server Core installation)

Weakness classification (CWE)

CWE-400 — Uncontrolled Resource Consumption

Public proof-of-concept exploits

References

portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-0820 (Patch, Vendor Advisory)
access.redhat.com/errata/RHSA-2019:1259 (vendor-advisory, Third Party Advisory)

Frequently asked questions

What is CVE-2019-0820?: CVE-2019-0820 is a high-severity vulnerability in Microsoft .Net Framework 2.0, classified under Uncontrolled Resource Consumption. CVSS score: 7.5/10. Published 2019-05-16.
How severe is CVE-2019-0820?: High severity. CVSS v3 base score is 7.5 out of 10.
Is CVE-2019-0820 known to be exploited?: 6 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.