Denial of Service (DoS) Affecting @openzeppelin/contracts package, versions >=3.2.0 <4.8.3



    Attack Complexity High

    Threat Intelligence

    EPSS 0.05% (18th percentile)
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5.3 medium

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  • published 18 Apr 2023
  • disclosed 17 Apr 2023
  • credit Unknown

How to fix?

Upgrade @openzeppelin/contracts to version 4.8.3 or higher.


@openzeppelin/contracts is a library for contract development.

Affected versions of this package are vulnerable to Denial of Service (DoS) such that a function in the implementation contract may be inaccessible if its selector clashes with one of the proxy's own selectors. Specifically, if the clashing function has a different signature with incompatible ABI encoding, the proxy could revert while attempting to decode the arguments from calldata.


If a function appears to be inaccessible for this reason, it may be possible to craft the calldata such that ABI decoding does not fail at the proxy and the function is properly proxied through.


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