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Fencer Vulns
high 7.5

CVE-2021-31957 json

ASP.NET Core Denial of Service Vulnerability

published 2021-06-08 5 y ago modified 2026-10-07 32 d ago also BIT-dotnet-2021-31957 , BIT-dotnet-sdk-2021-31957 , EUVD-2021-2231 , GHSA-mcwm-2wmc-6hv4

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
5.1%
EPSS 5.1% chance of exploitation in 30 days, percentile 92%
public exploits
0
none known

Summary

ASP.NET Core Denial of Service Vulnerability

Patch / fix

  • bitnami dotnet 5.0.7
  • bitnami dotnet-sdk 5.0.7
  • Microsoft Microsoft Visual Studio 2019 version 16.4 (includes 16.0 - 16.3) 16.4.23
  • Microsoft Microsoft Visual Studio 2019 version 16.7 (includes 16.0 – 16.6) 16.7.16
  • Microsoft Microsoft Visual Studio 2019 version 16.9 (includes 16.0 - 16.8) 16.9.7
  • Microsoft Microsoft Visual Studio 2019 version 16.10 (includes 16.0 - 16.9) 16.10.1
  • Microsoft Visual Studio 2019 for Mac version 8.10 8.10.1
  • Microsoft .NET Core 3.1 3.1.16
  • Microsoft .NET 5.0 5.0.7
  • dotnet RHEL 8 5.0.204-1.el8_4
  • dotnet5.0 RHEL 8 5.0.204-1.el8_4
  • dotnet-host RHEL 8 5.0.7-1.el8_4
  • dotnet-sdk-5.0 RHEL 8 5.0.204-1.el8_4
  • dotnet-hostfxr-5.0 RHEL 8 5.0.7-1.el8_4
  • dotnet-runtime-5.0 RHEL 8 5.0.7-1.el8_4
  • dotnet-templates-5.0 RHEL 8 5.0.204-1.el8_4
  • aspnetcore-runtime-5.0 RHEL 8 5.0.7-1.el8_4

red hat advisories RHSA-2021:2353RHSA-2021:2350RHSA-2021:2352RHSA-2021:2351

  • aspnet-runtime Arch Linux 5.0.7.sdk204-1

arch linux advisories AVG-2046

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-2021-31957 updated cvss 5.9

dotnet: ASP.NET Core Client Disconnect Denial of Service

  • Red Hat .NET Core on Red Hat Enterprise Linux ComputeNode (v. 7) rh-dotnet31-dotnet 3.1.116-1.el7_9, rh-dotnet50-dotnet 5.0.204-1.el7_9, rh-dotnet50-dotnet-host 5.0.7-1.el7_9, rh-dotnet31-dotnet-host 3.1.16-1.el7_9, rh-dotnet31-dotnet-sdk-3.1 3.1.116-1.el7_9, rh-dotnet50-dotnet-sdk-5.0 5.0.204-1.el7_9, +16 more Red Hat .NET Core on Red Hat Enterprise Linux Server (v. 7) rh-dotnet31-dotnet 3.1.116-1.el7_9, rh-dotnet50-dotnet 5.0.204-1.el7_9, rh-dotnet50-dotnet-host 5.0.7-1.el7_9, rh-dotnet31-dotnet-host 3.1.16-1.el7_9, rh-dotnet31-dotnet-sdk-3.1 3.1.116-1.el7_9, rh-dotnet50-dotnet-sdk-5.0 5.0.204-1.el7_9, +16 more Red Hat .NET Core on Red Hat Enterprise Linux Workstation (v. 7) rh-dotnet31-dotnet 3.1.116-1.el7_9, rh-dotnet50-dotnet 5.0.204-1.el7_9, rh-dotnet50-dotnet-host 5.0.7-1.el7_9, rh-dotnet31-dotnet-host 3.1.16-1.el7_9, rh-dotnet31-dotnet-sdk-3.1 3.1.116-1.el7_9, rh-dotnet50-dotnet-sdk-5.0 5.0.204-1.el7_9, +16 more
    fixed: vendor fix RHSA-2021:2350
  • Red Hat Enterprise Linux AppStream (v. 8) dotnet 5.0.204-1.el8_4, dotnet-host 5.0.7-1.el8_4, dotnet3.1 3.1.116-1.el8_4, dotnet5.0 5.0.204-1.el8_4, dotnet-sdk-3.1 3.1.116-1.el8_4, dotnet-sdk-5.0 5.0.204-1.el8_4, +15 more
    fixed: vendor fix RHSA-2021:2352
  • Red Hat .NET Core 2.1 on Red Hat Enterprise Linux rh-dotnet21, rh-dotnet21-runtime Red Hat Enterprise Linux 8 dotnet, dotnet-host, dotnet-sdk-2.1, dotnet-runtime-2.1, dotnet-sdk-2.1.5xx, dotnet-host-fxr-2.1
    not affected: vulnerable code not present

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

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
33 d ago

Exploit prediction

5.14% chance of exploitation in the next 30 days, higher than 92% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C
CNA 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA 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
OSV 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
bitnami dotnet
>=5.0.0, <5.0.7
5.0.7
bitnami dotnet-sdk
>=5.0.0, <5.0.7
5.0.7

Affected products

  • Microsoft Microsoft Visual Studio 2019 version 16.4 (includes 16.0 - 16.3)
  • Microsoft Microsoft Visual Studio 2019 version 16.7 (includes 16.0 – 16.6)
  • Microsoft Microsoft Visual Studio 2019 version 16.9 (includes 16.0 - 16.8)
  • Microsoft Microsoft Visual Studio 2019 version 16.10 (includes 16.0 - 16.9)
  • Microsoft Visual Studio 2019 for Mac version 8.10
  • Microsoft .NET Core 3.1
  • Microsoft .NET 5.0

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption

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.