Denial of Service (DoS) Affecting package, versions [1,1.0.4) [1.1,1.1.3)



    Attack Complexity Low
    Integrity High

    Threat Intelligence

    EPSS 0.35% (68th percentile)
Expand this section
7.5 high

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  • published 9 May 2017
  • disclosed 9 May 2017
  • credit David Fernandez

How to fix?

Upgrade Microsoft.AspNetCore.Mvc.Razor.Host to version 1.0.4, 1.1.3 or higher.


Microsoft.AspNetCore.Mvc.Razor.Host is a design time hosting infrastructure for the Razor view engine.

Affected versions of this package are vulnerable to Denial of Service (DoS) attacks.

A denial of service vulnerability exists when the ASP.NET Core fails to properly validate web requests.

NOTE: Microsoft has not commented on third-party claims that the issue is that the TextEncoder.EncodeCore function in the System.Text.Encodings.Web package in ASP.NET Core Mvc before 1.0.4 and 1.1.x before 1.1.3 allows remote attackers to cause a denial of service by leveraging failure to properly calculate the length of 4-byte characters in the Unicode Non-Character range.


Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

  • High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

  • Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package