A security feature bypass vulnerability exists in the way Microsoft ASP.NET Core parses encoded cookie names. The ASP.NET Core cookie parser decodes entire cookie strings which could allow a malicious attacker to set a second cookie with the name being percent encoded. The security update addresses the vulnerability by fixing the way the ASP.NET Core cookie parser handles encoded names.

An update of the dotnet package has been released.

The remote NewStart CGSL host, running version MAIN 6.02, has dotnet3.1 packages installed that are affected by a vulnerability:

  - A security feature bypass vulnerability exists in the way Microsoft ASP.NET Core parses encoded cookie     names.The ASP.NET Core cookie parser decodes entire cookie strings which could allow a malicious attacker     to set a second cookie with the name being percent encoded.The security update addresses the vulnerability     by fixing the way the ASP.NET Core cookie parser handles encoded names., aka 'Microsoft ASP.NET Core     Security Feature Bypass Vulnerability'. (CVE-2020-1045)

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

This update updates .NET Core 3.1 to SDK 3.1.108 and Runtime 3.1.8.

This update includes a fix for CVE-2020-1045

Release Notes:
https://github.com/dotnet/core/blob/master/release-notes/3.1/3.1.8/3.1 .8.md

Note that Tenable Network Security has extracted the preceding description block directly from the Fedora update system website.
Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

The remote Oracle Linux 8 host has packages installed that are affected by a vulnerability as referenced in the ELSA-2020-3699 advisory.

    [3.1.108-2.0.1.el8_2]
    - Update patch to support 8.2 (alexander.burmashev@oracle.com)
    - support OL release scheme (alexander.burmashev@oracle.com)

    [3.1.108-2]
    - Rebuild to fix tests
    - Resolves: RHBZ#1874512

    [3.1.108-1]
    - Update to .NET Core Runtime 3.1.8 and SDK 3.1.108
    - Resolves: RHBZ#1874512

Tenable has extracted the preceding description block directly from the Oracle Linux security advisory.

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

The remote Redhat Enterprise Linux 7 host has packages installed that are affected by a vulnerability as referenced in the RHSA-2020:3697 advisory.

    .NET Core is a managed-software framework. It implements a subset of the .NET framework APIs and several     new APIs, and it includes a CLR implementation.

    New versions of .NET Core that address a security vulnerability are now available. The updated versions     are .NET Core SDK 3.1.108 and .NET Core Runtime 3.1.8.

    Security Fix(es):

    * .NET Core: ASP.NET cookie prefix spoofing vulnerability (CVE-2020-1045)

    Default inclusions for applications built with .NET Core have been updated to reference the newest     versions and their security fixes.

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and     other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

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

The remote Redhat Enterprise Linux 8 host has packages installed that are affected by a vulnerability as referenced in the RHSA-2020:3699 advisory.

    .NET Core is a managed-software framework. It implements a subset of the .NET framework APIs and several     new APIs, and it includes a CLR implementation.

    New versions of .NET Core that address security vulnerabilities are now available. The updated versions     are .NET Core SDK 3.1.108 and .NET Core Runtime 3.1.8.

    Security Fixes:

    * .NET Core: ASP.NET cookie prefix spoofing vulnerability (CVE-2020-1045)

    Default inclusions for applications built with .NET Core have been updated to reference the newest     versions and their security fixes.

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and     other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

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

The Microsoft ASP.NET Core installation on the remote host is version 2.1.x < 2.1.22, or 3.1.x < 3.1.8. It is, therefore, affected by a security feature bypass vulnerability in the way ASP.NET Core parses encoded cookie names. An unauthenticated, remote attacker can exploit this issue, by sending a specially crafted cookies to the ASP.NET Core application to set a second cookie.

ID	Name	Product	Family	Severity
237067	Photon OS 4.0: Dotnet PHSA-2025-4.0-0804	Nessus	PhotonOS Local Security Checks	high
147317	NewStart CGSL MAIN 6.02 : dotnet3.1 Vulnerability (NS-SA-2021-0078)	Nessus	NewStart CGSL Local Security Checks	high
141267	Fedora 33 : dotnet3.1 (2020-48fa1ad65c)	Nessus	Fedora Local Security Checks	high
140625	Fedora 32 : dotnet3.1 (2020-e2deb72e0f)	Nessus	Fedora Local Security Checks	high
140498	Oracle Linux 8 : .NET / Core / 3.1 (ELSA-2020-3699)	Nessus	Oracle Linux Local Security Checks	high
140435	RHEL 7 : .NET Core 3.1 security and bugfix update for Red Hat Enterprise Linux (Important) (RHSA-2020:3697)	Nessus	Red Hat Local Security Checks	high
140434	RHEL 8 : .NET Core 3.1 (RHSA-2020:3699)	Nessus	Red Hat Local Security Checks	high
140425	Security Update for Microsoft ASP.NET Core (September 2020)	Nessus	Windows	high

Detections

Analytics

CVE-2020-1045

high

Tenable Plugins

high

high

high

high

high

high

high

high