GHSA-hxrm-9w7p-39cc BIT-aspnet-core-2020-1045 CVE-2020-1045
Cookie parsing failure
High
NuGet
- Severity
- 7.5 / 10
- High · CVSS 3.1
- Exploit chance (EPSS)
- 5.93%
- Chance of exploitation in the next 30 days. Higher than 93.25% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- —
- Not classified
- Fix
- Available
- 13 packages have a fixed version
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'.
Affected versions
NuGet
| Package | Vulnerable | Fixed in |
|---|---|---|
| Microsoft.AspNetCore.App | < 2.1.22 |
2.1.22 |
| Microsoft.AspNetCore.App.Runtime.linux-arm | >= 3.1.0, < 3.1.8 |
3.1.8 |
| Microsoft.AspNetCore.App.Runtime.linux-arm64 | >= 3.1.0, < 3.1.8 |
3.1.8 |
| Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 | >= 3.1.0, < 3.1.8 |
3.1.8 |
| Microsoft.AspNetCore.App.Runtime.linux-musl-x64 | >= 3.1.0, < 3.1.8 |
3.1.8 |
| Microsoft.AspNetCore.App.Runtime.linux-x64 | >= 3.1.0, < 3.1.8 |
3.1.8 |
| Microsoft.AspNetCore.App.Runtime.osx-x64 | >= 3.1.0, < 3.1.8 |
3.1.8 |
| Microsoft.AspNetCore.App.Runtime.win-arm | >= 3.1.0, < 3.1.8 |
3.1.8 |
| Microsoft.AspNetCore.App.Runtime.win-arm64 | >= 3.1.5, < 3.1.8 |
3.1.8 |
| Microsoft.AspNetCore.App.Runtime.win-x64 | >= 3.1.0, < 3.1.8 |
3.1.8 |
| Microsoft.AspNetCore.App.Runtime.win-x86 | >= 3.1.0, < 3.1.8 |
3.1.8 |
| Microsoft.AspNetCore.Http | < 2.1.22 |
2.1.22 |
| Microsoft.Owin | < 4.1.1 |
4.1.1 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
Microsoft.AspNetCore.App NuGet → 2.1.22
- dotnet
dotnet add package Microsoft.AspNetCore.App --version 2.1.22
Microsoft.AspNetCore.App.Runtime.linux-arm NuGet → 3.1.8
- dotnet
dotnet add package Microsoft.AspNetCore.App.Runtime.linux-arm --version 3.1.8
Microsoft.AspNetCore.App.Runtime.linux-arm64 NuGet → 3.1.8
- dotnet
dotnet add package Microsoft.AspNetCore.App.Runtime.linux-arm64 --version 3.1.8
Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 NuGet → 3.1.8
- dotnet
dotnet add package Microsoft.AspNetCore.App.Runtime.linux-musl-arm64 --version 3.1.8
Microsoft.AspNetCore.App.Runtime.linux-musl-x64 NuGet → 3.1.8
- dotnet
dotnet add package Microsoft.AspNetCore.App.Runtime.linux-musl-x64 --version 3.1.8
Microsoft.AspNetCore.App.Runtime.linux-x64 NuGet → 3.1.8
- dotnet
dotnet add package Microsoft.AspNetCore.App.Runtime.linux-x64 --version 3.1.8
Microsoft.AspNetCore.App.Runtime.osx-x64 NuGet → 3.1.8
- dotnet
dotnet add package Microsoft.AspNetCore.App.Runtime.osx-x64 --version 3.1.8
Microsoft.AspNetCore.App.Runtime.win-arm NuGet → 3.1.8
- dotnet
dotnet add package Microsoft.AspNetCore.App.Runtime.win-arm --version 3.1.8
Microsoft.AspNetCore.App.Runtime.win-arm64 NuGet → 3.1.8
- dotnet
dotnet add package Microsoft.AspNetCore.App.Runtime.win-arm64 --version 3.1.8
Microsoft.AspNetCore.App.Runtime.win-x64 NuGet → 3.1.8
- dotnet
dotnet add package Microsoft.AspNetCore.App.Runtime.win-x64 --version 3.1.8
Microsoft.AspNetCore.App.Runtime.win-x86 NuGet → 3.1.8
- dotnet
dotnet add package Microsoft.AspNetCore.App.Runtime.win-x86 --version 3.1.8
Microsoft.AspNetCore.Http NuGet → 2.1.22
- dotnet
dotnet add package Microsoft.AspNetCore.Http --version 2.1.22
Microsoft.Owin NuGet → 4.1.1
- dotnet
dotnet add package Microsoft.Owin --version 4.1.1
Severity breakdown
CVSS 3.1 7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- High
- Availability
- None
References
Advisories
Other links
- github.com/dotnet/announcements/issues/165
- github.com/dotnet/aspnetcore/issues/25701
- github.com/dotnet/aspnetcore/issues/25701
- github.com/github/advisory-database/issues/302
- github.com/dotnet/aspnetcore/pull/24264
- access.redhat.com/errata/RHSA-2020:3699
- github.com/dotnet/core/blob/main/release-notes/3.1/3.1.8/3.1.8.md
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/5LN…
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ASI…
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/5LN2F…
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/ASICX…
- portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-1045
- security.snyk.io/vuln/SNYK-RHEL8-DOTNET-1439600
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-vmch-3w2x-vhgq .NET Denial of Service Vulnerability | High Known exploited | Also affects Microsoft.AspNetCore.App.Runtime.win-arm64 |
| GHSA-f4g7-52wc-p8x7 Microsoft Security Advisory CVE-2026-96236 - ASP.NET Core Denial of Service Vulnerability | High | Also affects Microsoft.AspNetCore.App.Runtime.linux-arm |
| GHSA-rv87-ccxw-8ggf Microsoft Security Advisory CVE-2026-88092 - ASP.NET Core Security Feature Bypass Vulnerability | Critical | Also affects Microsoft.AspNetCore.App.Runtime.linux-arm |
| GHSA-57xr-hfxx-jw5x Microsoft Security Advisory CVE-2026-70196 - ASP.NET Core Denial of Service Vulnerability | Medium | Also affects Microsoft.AspNetCore.App.Runtime.linux-arm |
| GHSA-fpq8-4vhr-rcxx Microsoft Security Advisory CVE-2026-70188 - ASP.NET Core Security Feature Bypass Vulnerability | Critical | Also affects Microsoft.AspNetCore.App.Runtime.linux-arm |
| GHSA-mf4x-w4gh-4656 Microsoft Security Advisory CVE-2026-70186 - ASP.NET Core Denial of Service Vulnerability | High | Also affects Microsoft.AspNetCore.App.Runtime.linux-arm |
| GHSA-494h-xx7x-5frh Microsoft Security Advisory CVE-2026-70183 - ASP.NET Core Security Feature Bypass Vulnerability | High | Also affects Microsoft.AspNetCore.App.Runtime.linux-arm |
| GHSA-w5qq-qrpp-rf4c Microsoft Security Advisory CVE-2026-70181 - ASP.NET Core Denial of Service Vulnerability | High | Also affects Microsoft.AspNetCore.App.Runtime.linux-arm |
MergeHarbor checks every repository's dependencies against this database, ranks what matters by exploitability and reachability, routes it to the owning team and opens the fix pull request.
Check your repos with MergeHarbor