# CVE-2017-8700: Cross-origin Resource Sharing bypass in ASP.NET Core

> Attackers can bypass CORS restrictions in ASP.NET Core to retrieve restricted content from web applications.

- **Severity:** High 7.5 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Nov 2017
- **Updated:** 16 Sep 2024
- **Also known as:** ECHO-06b1-ea74-05f0, GHSA-3rp6-rjw4-cq39

## What is CVE-2017-8700?

CVE-2017-8700 is a high-severity vulnerability in Microsoft Corporation ASP.NET Core, published on 15 Nov 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

ASP.NET Core 1.0, 1.1, and 2.0 allow an attacker to bypass Cross-origin Resource Sharing (CORS) configurations and retrieve normally restricted content from a web application, aka "ASP.NET Core Information Disclosure Vulnerability".

## Which versions are affected by CVE-2017-8700?

8 open source packages ship an affected version, including Microsoft.AspNetCore.Mvc.Core and Microsoft.AspNetCore.Mvc.Cors. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `Microsoft.AspNetCore.Mvc.Core` | NuGet | From 1.0.0 | 1.0.6 |
| `Microsoft.AspNetCore.Mvc.Core` | NuGet | From 1.0.0 | 1.0.6 |
| `Microsoft.AspNetCore.Mvc.Core` | NuGet | From 1.1.0 | 1.1.6 |
| `Microsoft.AspNetCore.Mvc.Core` | NuGet | From 1.1.0 | 1.1.6 |
| `Microsoft.AspNetCore.Mvc.Cors` | NuGet | From 1.0.0 | 1.0.6 |
| `Microsoft.AspNetCore.Mvc.Cors` | NuGet | From 1.0.0 | 1.0.6 |
| `Microsoft.AspNetCore.Mvc.Cors` | NuGet | From 1.1.0 | 1.1.6 |
| `Microsoft.AspNetCore.Mvc.Cors` | NuGet | From 1.1.0 | 1.1.6 |

Products: Microsoft Asp.net Core.

## How do I fix CVE-2017-8700?

Upgrade Microsoft.AspNetCore.Mvc.Core to a fixed version for your release line: 1.0.6 or 1.1.6.

## Is CVE-2017-8700 being exploited?

There is no known exploitation of CVE-2017-8700 in the wild and no public exploit code.

## Other vulnerabilities in Microsoft Corporation ASP.NET Core

- [CVE-2025-55315](https://insights.sbomify.com/CVE-2025-55315/): ASP.NET Security Feature Bypass Vulnerability (critical 9.9)
- [CVE-2026-88092](https://insights.sbomify.com/CVE-2026-88092/): ASP.NET Core Tampering Vulnerability (critical 9.4)
- [CVE-2026-40372](https://insights.sbomify.com/CVE-2026-40372/): ASP.NET Core Elevation of Privilege Vulnerability (critical 9.1)
- [CVE-2021-43877](https://insights.sbomify.com/CVE-2021-43877/): ASP.NET Core and Visual Studio Elevation of Privilege Vulnerability (high 8.8)
- [CVE-2020-0603](https://insights.sbomify.com/CVE-2020-0603/): Remote code execution in ASP.NET Core (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2017-8700 and fix it if it is affected.

What it is: CVE-2017-8700 is a high-severity vulnerability in Microsoft Corporation ASP.NET Core, published on 15 Nov 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2017-8700 in the wild and no public exploit code.

Affected packages and fixed versions:
- Microsoft.AspNetCore.Mvc.Core (NuGet): affected from 1.0.0; fixed in 1.0.6
- Microsoft.AspNetCore.Mvc.Core (NuGet): affected from 1.0.0; fixed in 1.0.6
- Microsoft.AspNetCore.Mvc.Core (NuGet): affected from 1.1.0; fixed in 1.1.6
- Microsoft.AspNetCore.Mvc.Core (NuGet): affected from 1.1.0; fixed in 1.1.6
- Microsoft.AspNetCore.Mvc.Cors (NuGet): affected from 1.0.0; fixed in 1.0.6
- Microsoft.AspNetCore.Mvc.Cors (NuGet): affected from 1.0.0; fixed in 1.0.6
- Microsoft.AspNetCore.Mvc.Cors (NuGet): affected from 1.1.0; fixed in 1.1.6
- Microsoft.AspNetCore.Mvc.Cors (NuGet): affected from 1.1.0; fixed in 1.1.6

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2017-8700/ (Markdown: https://insights.sbomify.com/CVE-2017-8700/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2017-8700
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2017-8700
- OSV: https://osv.dev/vulnerability/CVE-2017-8700

---
From sbomify Insights: https://insights.sbomify.com/CVE-2017-8700/
Summaries are generated and may contain mistakes; the official description above is the record.