Security Update for .NET Core (August 2021)

high Nessus Plugin ID 152488

Synopsis

The remote Windows host is affected by a .NET Core denial of service (DoS) vulnerability.

Description

The Microsoft .NET Core installation on the remote host is version 2.1.x prior to 2.1.29, 3.1.x prior to 3.1.18, or 5.x prior to 5.0.9. It is, therefore affected by a denial of service (DoS) vulnerability, as server applications providing WebSocket endpoints can be tricked into endlessly looping while trying to read a single WebSocket frame.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Update .NET Core, remove vulnerable packages and refer to vendor advisory.

See Also

https://dotnet.microsoft.com/download/dotnet/2.1

https://dotnet.microsoft.com/download/dotnet-core/3.1

https://dotnet.microsoft.com/download/dotnet/5.0

http://www.nessus.org/u?8ff12246

http://www.nessus.org/u?0933ffe1

http://www.nessus.org/u?6242d65f

https://devblogs.microsoft.com/dotnet/net-august-2021/

Plugin Details

Severity: High

ID: 152488

File Name: smb_nt_ms21_aug_dotnet_core.nasl

Version: 1.4

Type: local

Agent: windows

Family: Windows

Published: 8/11/2021

Updated: 8/20/2021

Supported Sensors: Frictionless Assessment Agent, Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Low

Score: 3.6

CVSS v2

Risk Factor: Medium

Base Score: 5

Temporal Score: 3.7

Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P

CVSS Score Source: CVE-2021-26423

CVSS v3

Risk Factor: High

Base Score: 7.5

Temporal Score: 6.5

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/a:microsoft:.net_core

Required KB Items: installed_sw/.NET Core Windows

Exploit Ease: No known exploits are available

Patch Publication Date: 8/10/2021

Vulnerability Publication Date: 8/10/2021

Reference Information

CVE: CVE-2021-26423

IAVA: 2021-A-0379