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URL: https://nvd.nist.gov/vuln/detail/CVE-2020-1045

⇱ NVD - CVE-2020-1045

  1. Vulnerabilities

CVE-2020-1045 Detail

Modified After Enrichment

This CVE record has been updated after NVD enrichment efforts were completed. Enrichment data supplied by the NVD may require amendment due to these changes.

Current Description

<p>A security feature bypass vulnerability exists in the way Microsoft ASP.NET Core parses encoded cookie names.</p> <p>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.</p> <p>The security update addresses the vulnerability by fixing the way the ASP.NET Core cookie parser handles encoded names.</p>


View Analysis Description

Analysis Description

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'.

Metrics

 
NVD enrichment efforts reference publicly available information to associate vector strings. CVSS information contributed by other sources is also displayed.
CVSS 4.0 Severity and Vector Strings:

NVD assessment not yet provided.

References to Advisories, Solutions, and Tools

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URL Source(s) Tag(s)
https://access.redhat.com/errata/RHSA-2020:3699 CVE, Microsoft Corporation Third Party Advisory 
https://github.com/dotnet/core/blob/main/release-notes/3.1/3.1.8/3.1.8.md#changes-in-318 CVE, Microsoft Corporation Release Notes  Third Party Advisory 
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/5LN2FUVBSVPGK7AU3NMLO3YR6CGONQPB/ CVE, Microsoft Corporation
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ASICXQXS4M7MTAF6SGQMCLCA63DLCUT3/ CVE, Microsoft Corporation
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-1045 CVE, Microsoft Corporation Patch  Vendor Advisory 
https://security.snyk.io/vuln/SNYK-RHEL8-DOTNET-1439600 CVE, Microsoft Corporation Third Party Advisory 

Weakness Enumeration

CWE-ID CWE Name Source
NVD-CWE-noinfo Insufficient Information 👁 cwe source acceptance level
NIST  

Known Affected Software Configurations Switch to CPE 2.2

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Denotes Vulnerable Software
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Change History

14 change records found show changes

CVE Modified by CISA-ADP 6/16/2026 11:00:18 PM

Action Type Old Value New Value
Added SSVC 
{"timestamp":"2024-01-10T18:21:43.315688Z","id":"CVE-2020-1045","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}

CVE Modified by Microsoft Corporation 6/16/2026 11:00:18 PM

Action Type Old Value New Value
Added Affected 
[{"vendor":"Microsoft","product":"ASP.NET Core 2.1","cpes":["cpe:2.3:a:microsoft:asp.net_core:2.1*:*:*:*:*:*:*:*"],"platforms":["Unknown"],"versions":[{"version":"2.0","lessThan":"publication","versionType":"custom","status":"affected"}]},{"vendor":"Microsoft","product":"ASP.NET Core 3.1","cpes":["cpe:2.3:a:microsoft:asp.net_core:3.1:*:*:*:*:*:*:*"],"platforms":["Unknown"],"versions":[{"version":"3.0","lessThan":"publication","versionType":"custom","status":"affected"}]}]

CVE Modified by Microsoft Corporation 2/23/2026 1:23:07 PM

Action Type Old Value New Value
Changed Description 
<p>A security feature bypass vulnerability exists in the way Microsoft ASP.NET Core parses encoded cookie names.</p>
<p>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.</p>
<p>The security update addresses the vulnerability by fixing the way the ASP.NET Core cookie parser handles encoded names.</p>



<p>A security feature bypass vulnerability exists in the way Microsoft ASP.NET Core parses encoded cookie names.</p>
<p>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.</p>
<p>The security update addresses the vulnerability by fixing the way the ASP.NET Core cookie parser handles encoded names.</p>

CVE Modified by CVE 11/21/2024 12:09:37 AM

Action Type Old Value New Value
Added Reference 
https://access.redhat.com/errata/RHSA-2020:3699
Added Reference 
https://github.com/dotnet/core/blob/main/release-notes/3.1/3.1.8/3.1.8.md#changes-in-318
Added Reference 
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/5LN2FUVBSVPGK7AU3NMLO3YR6CGONQPB/
Added Reference 
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ASICXQXS4M7MTAF6SGQMCLCA63DLCUT3/
Added Reference 
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-1045
Added Reference 
https://security.snyk.io/vuln/SNYK-RHEL8-DOTNET-1439600

CVE Modified by Microsoft Corporation 5/14/2024 2:38:05 AM

Action Type Old Value New Value

CVE Modified by Microsoft Corporation 12/31/2023 5:15:55 PM

Action Type Old Value New Value
Changed Description 
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'.


 
<p>A security feature bypass vulnerability exists in the way Microsoft ASP.NET Core parses encoded cookie names.</p>
<p>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.</p>
<p>The security update addresses the vulnerability by fixing the way the ASP.NET Core cookie parser handles encoded names.</p>


Added CVSS V3.1 
Microsoft Corporation AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CVE Modified by Microsoft Corporation 11/06/2023 10:19:19 PM

Action Type Old Value New Value
Added Reference 
Microsoft Corporation https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/5LN2FUVBSVPGK7AU3NMLO3YR6CGONQPB/ [No types assigned]
Added Reference 
Microsoft Corporation https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ASICXQXS4M7MTAF6SGQMCLCA63DLCUT3/ [No types assigned]
Removed Reference 
Microsoft Corporation https://lists.fedoraproject.org/archives/list/[email protected]/message/5LN2FUVBSVPGK7AU3NMLO3YR6CGONQPB/
Removed Reference 
Microsoft Corporation https://lists.fedoraproject.org/archives/list/[email protected]/message/ASICXQXS4M7MTAF6SGQMCLCA63DLCUT3/

Modified Analysis by NIST 12/12/2022 1:29:37 PM

Action Type Old Value New Value
Added CPE Configuration 
OR
 *cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
 *cpe:2.3:o:redhat:enterprise_linux_aus:8.2:*:*:*:*:*:*:*
 *cpe:2.3:o:redhat:enterprise_linux_aus:8.4:*:*:*:*:*:*:*
 *cpe:2.3:o:redhat:enterprise_linux_aus:8.6:*:*:*:*:*:*:*
 *cpe:2.3:o:redhat:enterprise_linux_eus:8.2:*:*:*:*:*:*:*
 *cpe:2.3:o:redhat:enterprise_linux_eus:8.4:*:*:*:*:*:*:*
 *cpe:2.3:o:redhat:enterprise_linux_eus:8.6:*:*:*:*:*:*:*
 *cpe:2.3:o:redhat:enterprise_linux_tus:8.2:*:*:*:*:*:*:*
 *cpe:2.3:o:redhat:enterprise_linux_tus:8.4:*:*:*:*:*:*:*
 *cpe:2.3:o:redhat:enterprise_linux_tus:8.6:*:*:*:*:*:*:*
Changed Reference Type 
https://access.redhat.com/errata/RHSA-2020:3699 No Types Assigned


 
https://access.redhat.com/errata/RHSA-2020:3699 Third Party Advisory
Changed Reference Type 
https://github.com/dotnet/core/blob/main/release-notes/3.1/3.1.8/3.1.8.md#changes-in-318 No Types Assigned


 
https://github.com/dotnet/core/blob/main/release-notes/3.1/3.1.8/3.1.8.md#changes-in-318 Release Notes, Third Party Advisory
Changed Reference Type 
https://security.snyk.io/vuln/SNYK-RHEL8-DOTNET-1439600 No Types Assigned


 
https://security.snyk.io/vuln/SNYK-RHEL8-DOTNET-1439600 Third Party Advisory

CVE Modified by Microsoft Corporation 11/23/2022 1:15:10 PM

Action Type Old Value New Value
Added Reference 
https://access.redhat.com/errata/RHSA-2020:3699 [No Types Assigned]
Added Reference 
https://github.com/dotnet/core/blob/main/release-notes/3.1/3.1.8/3.1.8.md#changes-in-318 [No Types Assigned]
Added Reference 
https://security.snyk.io/vuln/SNYK-RHEL8-DOTNET-1439600 [No Types Assigned]

Reanalysis by NIST 11/21/2022 3:02:13 PM

Action Type Old Value New Value
Changed CPE Configuration 
OR
 *cpe:2.3:a:microsoft:asp.net_core:2.1:*:*:*:*:*:*:*
 *cpe:2.3:a:microsoft:asp.net_core:3.1:*:*:*:*:*:*:*


 
OR
 *cpe:2.3:a:microsoft:asp.net_core:*:*:*:*:*:*:*:* versions from (including) 2.1 up to (including) 2.1.21
 *cpe:2.3:a:microsoft:asp.net_core:*:*:*:*:*:*:*:* versions from (including) 3.1 up to (excluding) 3.1.8

Modified Analysis by NIST 9/02/2022 11:34:57 AM

Action Type Old Value New Value
Added CPE Configuration 
OR
 *cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
 *cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
Changed Reference Type 
https://lists.fedoraproject.org/archives/list/[email protected]/message/5LN2FUVBSVPGK7AU3NMLO3YR6CGONQPB/ No Types Assigned


 
https://lists.fedoraproject.org/archives/list/[email protected]/message/5LN2FUVBSVPGK7AU3NMLO3YR6CGONQPB/ Mailing List, Third Party Advisory
Changed Reference Type 
https://lists.fedoraproject.org/archives/list/[email protected]/message/ASICXQXS4M7MTAF6SGQMCLCA63DLCUT3/ No Types Assigned


 
https://lists.fedoraproject.org/archives/list/[email protected]/message/ASICXQXS4M7MTAF6SGQMCLCA63DLCUT3/ Mailing List, Third Party Advisory

CVE Modified by Microsoft Corporation 10/01/2020 11:15:14 PM

Action Type Old Value New Value
Added Reference 
https://lists.fedoraproject.org/archives/list/[email protected]/message/ASICXQXS4M7MTAF6SGQMCLCA63DLCUT3/ [No Types Assigned]

CVE Modified by Microsoft Corporation 9/16/2020 1:15:13 PM

Action Type Old Value New Value
Added Reference 
https://lists.fedoraproject.org/archives/list/[email protected]/message/5LN2FUVBSVPGK7AU3NMLO3YR6CGONQPB/ [No Types Assigned]

Initial Analysis by NIST 9/16/2020 9:38:11 AM

Action Type Old Value New Value
Added CVSS V3.1 
NIST AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Added CVSS V2 
NIST (AV:N/AC:L/Au:N/C:N/I:P/A:N)
Added CWE 
NIST NVD-CWE-noinfo
Added CPE Configuration 
OR
 *cpe:2.3:a:microsoft:asp.net_core:2.1:*:*:*:*:*:*:*
 *cpe:2.3:a:microsoft:asp.net_core:3.1:*:*:*:*:*:*:*
Changed Reference Type 
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-1045 No Types Assigned


 
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-1045 Patch, Vendor Advisory

Quick Info

CVE Dictionary Entry:
CVE-2020-1045
NVD Published Date:
09/11/2020
NVD Last Modified:
06/16/2026
Source:
Microsoft Corporation