# CVE-2020-8192: Fastify denial of service via allErrors schema validation option

Source: https://junglewise.ai/threats/cve-2020-8192-fastify-denial-of-service-via-allerrors-schema-validation-option  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2020-08-05. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2020-8192 · Severity: info · CVSS 5.3 · Published 2020-08-05

Fastify is a popular Node.js web framework used to build fast APIs and web applications. A vulnerability in versions 2.14.1 and 3.0.0-rc.4 allows attackers to cause resource exhaustion and service outages by sending specially crafted schema validation requests when the allErrors option is enabled. This could impact the availability and responsiveness of web services built on affected Fastify versions.

Technologies: [fastify (npm)](https://junglewise.ai/threats/technologies/fastify). Vendors: [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is CVE-2020-8192 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2020-8192 being exploited in the wild.

**How severe is CVE-2020-8192?** Informational severity, with a CVSS score of 5.3, published 5 August 2020.

**Which products and versions are affected?** fastify (npm) SEMVER:introduced=0,fixed=2.15.1.

**Is there a fix for CVE-2020-8192?** Yes. fastify (npm): upgrade to 2.15.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2020-8192 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2020-8192?** Check whether you run fastify (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- fastify (npm): upgrade to 2.15.1 or later

  ```sh
  npm install fastify@2.15.1
  ```


## Technical details

The vulnerability is a resource exhaustion / denial-of-service condition in Fastify's JSON schema validation logic, specifically when the allErrors option is enabled in the Ajv validator configuration. An attacker can craft malicious schemas that trigger excessive validation error collection, consuming CPU and memory resources. The attack requires no authentication and is network-reachable; the attacker needs only to send HTTP requests with payloads that match the vulnerable schema patterns. The impact is service degradation or complete unavailability. The fix disables allErrors in the default Ajv configuration (patched in 2.15.1).

## Affected products

- Fastify fastify 0 through 2.15.0, 3.0.0-rc.1 through 3.0.0-rc.4

## Identifiers

- CVE-2020-8192
- GHSA-xw5p-hw6r-2j98

## Timeline

- 2020-08-05: disclosed
- 2020-08-05: patched: Fastify 2.15.1 released with fix

## References

- [https://github.com/fastify/fastify/commit/74c3157ca90c3ffed9e4434f63c2017471ec970e](https://github.com/fastify/fastify/commit/74c3157ca90c3ffed9e4434f63c2017471ec970e)

## Related threats

- [fastify is vulnerable to header validation bypass via case-sensitive propertyNames](https://junglewise.ai/threats/cve-2026-107832-fastify-is-a-fast-and-low-overhead-web-framework-for-node-js-in)
- [Fastify denial of service via unhandled exception on HTTP/2 trailer responses](https://junglewise.ai/threats/cve-2026-92081-fastify-denial-of-service-via-unhandled-exception-on-http-2)
- [Fastify header validation bypass via incomplete schema case normalization](https://junglewise.ai/threats/cve-2026-84428-fastify-header-validation-bypass-via-incomplete-schema-case)
- [Fastify request body replacement via async validation result collision](https://junglewise.ai/threats/cve-2026-84504-fastify-request-body-replacement-via-async-validation-result)
- [Fastify request validation bypass via skipped boolean false schemas](https://junglewise.ai/threats/cve-2026-84469-fastify-request-validation-bypass-via-skipped-boolean-false)