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Fencer Vulns
high 7.5

CVE-2019-0820 json

Regular Expression Denial of Service in System.Text.RegularExpressions

published 2019-05-16 7 y ago modified 2026-06-17 4 mo ago also GHSA-cmhx-cq75-c4mj , EUVD-2021-1682

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
5.7%
EPSS 5.7% chance of exploitation in 30 days, percentile 93%
public exploits
0
none known

Summary

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.

Patch / fix

  • nuget System.Text.RegularExpressions 4.3.1
  • rh-dotnet21 RHEL 2.1 DOTNET 2.1-10.el7
  • rh-dotnet22 RHEL 2.2 DOTNET 2.2-7.el7
  • rh-dotnet22-curl RHEL 2.2 DOTNET 7.61.1-2.el7
  • rh-dotnet21-dotnet RHEL 2.1 DOTNET 2.1.507-2.el7
  • rh-dotnet22-dotnet RHEL 2.2 DOTNET 2.2.107-2.el7
  • rh-dotnet21-runtime RHEL 2.1 DOTNET 2.1-10.el7
  • rh-dotnet22-libcurl RHEL 2.2 DOTNET 7.61.1-2.el7
  • rh-dotnet22-runtime RHEL 2.2 DOTNET 2.2-7.el7

red hat advisories RHSA-2019:1236RHSA-2019:1259

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2019-0820 updated cvss 7.5

dotnet: timeouts for regular expressions are not enforced

  • Red Hat .NET Core on Red Hat Enterprise Linux ComputeNode (v. 7) rh-dotnet22 2.2-7.el7, rh-dotnet21 2.1-10.el7, rh-dotnet22-curl 7.61.1-2.el7, rh-dotnet22-runtime 2.2-7.el7, rh-dotnet21-runtime 2.1-10.el7, rh-dotnet21-dotnet 2.1.507-2.el7, +13 more Red Hat .NET Core on Red Hat Enterprise Linux Server (v. 7) rh-dotnet22 2.2-7.el7, rh-dotnet21 2.1-10.el7, rh-dotnet22-curl 7.61.1-2.el7, rh-dotnet22-runtime 2.2-7.el7, rh-dotnet21-runtime 2.1-10.el7, rh-dotnet21-dotnet 2.1.507-2.el7, +13 more Red Hat .NET Core on Red Hat Enterprise Linux Workstation (v. 7) rh-dotnet22 2.2-7.el7, rh-dotnet21 2.1-10.el7, rh-dotnet22-curl 7.61.1-2.el7, rh-dotnet22-runtime 2.2-7.el7, rh-dotnet21-runtime 2.1-10.el7, rh-dotnet21-dotnet 2.1.507-2.el7, +13 more
    fixed: vendor fix RHSA-2019:1236
  • Red Hat Enterprise Linux AppStream (v. 8) dotnet 2.1.507-2.el8_0, dotnet-host 2.1.11-2.el8_0, dotnet-sdk-2.1 2.1.507-2.el8_0, dotnet-runtime-2.1 2.1.11-2.el8_0, dotnet-host-fxr-2.1 2.1.11-2.el8_0, dotnet-sdk-2.1.5xx 2.1.507-2.el8_0
    fixed: vendor fix RHSA-2019:1259

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

5.72% chance of exploitation in the next 30 days, higher than 93% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
nuget System.Text.RegularExpressions
>=4.3.0, <4.3.1
4.3.1

Affected products

  • Microsoft Microsoft .NET Framework 4.5.2
  • Microsoft Microsoft .NET Framework 4.6
  • Microsoft .NET Core
  • Microsoft Microsoft .NET Framework 4.7.2
  • Microsoft Microsoft .NET Framework 4.6/4.6.1/4.6.2/4.7/4.7.1/4.7.2
  • Microsoft Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2
  • Microsoft Microsoft .NET Framework 4.8 on Windows 7 for 32-bit Systems Service Pack 1
  • Microsoft Microsoft .NET Framework 4.8 on Windows 7 for x64-based Systems Service Pack 1
  • Microsoft Microsoft .NET Framework 4.8 on Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation)
  • Microsoft Microsoft .NET Framework 4.8 on Windows Server 2008 R2 for x64-based Systems Service Pack 1
  • Microsoft Microsoft .NET Framework 4.8 on Windows Server 2012
  • Microsoft Microsoft .NET Framework 4.8 on Windows Server 2012 (Server Core installation)
  • Microsoft Microsoft .NET Framework 4.8 on Windows 8.1 for 32-bit systems
  • Microsoft Microsoft .NET Framework 4.8 on Windows 8.1 for x64-based systems
  • Microsoft Microsoft .NET Framework 4.8 on Windows Server 2012 R2
  • Microsoft Microsoft .NET Framework 4.8 on Windows RT 8.1
  • Microsoft Microsoft .NET Framework 4.8 on Windows Server 2012 R2 (Server Core installation)
  • Microsoft Microsoft .NET Framework 4.8 on Windows Server 2016
  • Microsoft Microsoft .NET Framework 4.8 on Windows 10 Version 1607 for 32-bit Systems
  • Microsoft Microsoft .NET Framework 4.8 on Windows 10 Version 1607 for x64-based Systems
  • Microsoft Microsoft .NET Framework 4.8 on Windows Server 2016 (Server Core installation)
  • Microsoft Microsoft .NET Framework 4.8 on Windows 10 Version 1703 for 32-bit Systems
  • Microsoft Microsoft .NET Framework 4.8 on Windows 10 Version 1703 for x64-based Systems
  • Microsoft Microsoft .NET Framework 4.8 on Windows 10 Version 1709 for 32-bit Systems
  • Microsoft Microsoft .NET Framework 4.8 on Windows 10 Version 1709 for x64-based Systems
  • Microsoft Microsoft .NET Framework 4.8 on Windows 10 Version 1803 for 32-bit Systems
  • Microsoft Microsoft .NET Framework 4.8 on Windows 10 Version 1803 for x64-based Systems
  • Microsoft Microsoft .NET Framework 4.8 on Windows Server, version 1803 (Server Core Installation)
  • Microsoft Microsoft .NET Framework 4.8 on Windows 10 Version 1809 for 32-bit Systems
  • Microsoft Microsoft .NET Framework 4.8 on Windows 10 Version 1809 for x64-based Systems
  • Microsoft Microsoft .NET Framework 4.8 on Windows Server 2019
  • Microsoft Microsoft .NET Framework 4.8 on Windows Server 2019 (Server Core installation)
  • Microsoft Microsoft .NET Framework 4.8 on Windows 10 Version 1903 for 32-bit Systems
  • Microsoft Microsoft .NET Framework 4.8 on Windows 10 Version 1903 for x64-based Systems
  • Microsoft Microsoft .NET Framework 4.8 on Windows Server, version 1903 (Server Core installation)
  • Microsoft Microsoft .NET Framework 3.5
  • Microsoft Microsoft .NET Framework 3.5 on Windows 10 Version 1903 for 32-bit Systems
  • Microsoft Microsoft .NET Framework 3.5 on Windows 10 Version 1903 for x64-based Systems
  • Microsoft Microsoft .NET Framework 3.5 on Windows Server, version 1903 (Server Core installation)
  • Microsoft Microsoft .NET Framework 3.0
  • Microsoft Microsoft .NET Framework 2.0
  • Microsoft Microsoft .NET Framework 3.5.1

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption
  • CWE-1333 Inefficient Regular Expression Complexity

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.