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.NET
.NET NuGet
Not in CISA KEV
HIGH severity

CVE-2018-8171 — Microsoft.AspNetCore.Iden…

HIGH

CVE-2018-8171 is a high-severity (CVSS 7.5) Improper Authentication vulnerability in Microsoft.AspNetCore.Identity. EPSS puts its 30-day exploitation probability at 10.8% (96th percentile). A fix is available for Microsoft.AspNetCore.Identity — see the affected versions and patch details below.

Security feature bypass vulnerability exists in ASP.NET when the number of incorrect login attempts is not validated

Also known asGHSA-vhvh-528q-ff3p
Published
Updated
Affected
4 pkgs
Patched
4 / 4
Exploits
None indexed
Exploitation data as of Nov 7, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
10.8%probability of exploitation in next 30 days
Moderate Risk0.00%
Lower risk than most CVEs96th percentile — riskier than 96% of all scored CVEsHighest risk
3.54%11.0%18.5%26.0%21.8%10.8%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

4 pkgs affected
.NETMicrosoft.AspNetCore.Identity.NETMicrosoft.AspNetCore.Identity.NETMicrosoft.AspNetCore.Identity.NETMicrosoft.AspNetCore.Identity

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems.

Description

A Security Feature Bypass vulnerability exists in ASP.NET when the number of incorrect login attempts is not validated, aka "ASP.NET Security Feature Bypass Vulnerability." This affects ASP.NET, ASP.NET Core 1.1, ASP.NET Core 1.0, ASP.NET Core 2.0, ASP.NET MVC 5.2.

Affected Packages

4 total 4 fixed
EcosystemPackageVulnerable rangeFix
.NETNuGetMicrosoft.AspNetCore.Identity≥ 1.0.0&&< 1.0.61.0.6dotnet add package Microsoft.AspNetCore.Identity --version 1.0.6
.NETNuGetMicrosoft.AspNetCore.Identity≥ 1.1.0&&< 1.1.61.1.6dotnet add package Microsoft.AspNetCore.Identity --version 1.1.6
.NETNuGetMicrosoft.AspNetCore.Identity≥ 2.0.0&&< 2.0.42.0.4dotnet add package Microsoft.AspNetCore.Identity --version 2.0.4
.NETNuGetMicrosoft.AspNetCore.Identity≥ 2.1.0&&< 2.1.22.1.2dotnet add package Microsoft.AspNetCore.Identity --version 2.1.2

Affected Products

3 products · 5 configurations
Application
asp.net coremicrosoft
3 versions
1.01.12.0
Application
asp.net model view controllermicrosoft
1 version
5.2
Application
asp.net webpagesmicrosoft
1 version
3.2.3

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Microsoft.AspNetCore.Identity, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update Microsoft.AspNetCore.Identity to 1.0.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2018-8171 is resolved across your whole dependency graph.

  3. Workarounds

    Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Frequently Asked Questions

A Security Feature Bypass vulnerability exists in ASP.NET when the number of incorrect login attempts is not validated, aka "ASP.NET Security Feature Bypass Vulnerability." This affects ASP.NET, ASP.NET Core 1.1, ASP.NET Core 1.0, ASP.NET Core 2.0, ASP.NET MVC 5.2.
O3 Security · Impact-Aware SCA

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CVE-2018-8171: Microsoft.AspNetCore — Fixed in 1.0.6