Denial of Service (DoS) Affecting petero.cbor package, versions [,4.0.0)

  • Attack Complexity


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  • snyk-id


  • published

    28 Nov 2019

  • disclosed

    30 Sep 2019

  • credit


How to fix?

Upgrade PeterO.Cbor to version 4.0.0 or higher.


PeterO.Cbor is a C# implementation of Concise Binary Object Representation (CBOR).

Affected versions of this package are vulnerable to Denial of Service (DoS). The CBOR library supports optional tags that enable CBOR objects to contain references to objects within them and resolve these references automatically. A denial of service can happen if those references are deeply nested and used multiple times (so that the same reference to the same object occurs multiple times), and if the decoded CBOR object is sent to a serialization method such as EncodeToBytes, ToString, or ToJSONString, since the objects referred to are expanded in the process and take up orders of magnitude more memory than if the references were not resolved.


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