Denial of Service (DoS) Affecting yar package, versions <2.2.0



    Attack Complexity Low
    Availability High

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  • Snyk ID npm:yar:20140616
  • published 16 Jun 2014
  • disclosed 16 Jun 2014
  • credit Reid Burke

How to fix?

Update to a version 2.2.0 or greater.


Yar uses an encrypted cookie for session support, during the hapi request/reply flow if this cookie value is invalid (changed by the end-user), a request object variable is not set. In versions prior 2.2.0, the presence of this variable was not validated prior to use, resulting in an unhandled ReferenceError, which in most cases will crash the process.

Source: Node Security Project


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