CVE-2021-43801

Name: CVE-2021-43801
Creator: NVD / NIST
Published: 2021-12-13T20:15:07.577+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 1.52%

Last modified Jun 17, 2026

CVE-2021-43801 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. Mercurius is a GraphQL adapter for Fastify. Any users from Mercurius@8.10.0 to 8.11.1 are subjected to a denial of service attack by sending a malformed JSON to `/graphql` unless they are using a custom error handler. EPSS estimates a 1.52% chance of exploitation in the next 30 days.

Description

Mercurius is a GraphQL adapter for Fastify. Any users from Mercurius@8.10.0 to 8.11.1 are subjected to a denial of service attack by sending a malformed JSON to `/graphql` unless they are using a custom error handler. The vulnerability has been fixed in https://github.com/mercurius-js/mercurius/pull/678 and shipped as v8.11.2. As a workaround users may use a custom error handler.

Metrics

CVSS 3.1

7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

1.52%

71.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-754

Affected Software

Vendor	Product	Versions
Mercurius Project	Mercurius	>= 8.10.0, < 8.11.2

References

https://github.com/mercurius-js/mercurius/issues/677Issue Tracking, Patch, Third Party Advisory
https://github.com/mercurius-js/mercurius/pull/678/commits/732b2f895312da8deadd7b173dcd2d141d54b223Patch, Third Party Advisory
https://github.com/mercurius-js/mercurius/security/advisories/GHSA-273r-rm8g-7f3xPatch, Third Party Advisory
https://github.com/mercurius-js/mercurius/issues/677Issue Tracking, Patch, Third Party Advisory
https://github.com/mercurius-js/mercurius/pull/678/commits/732b2f895312da8deadd7b173dcd2d141d54b223Patch, Third Party Advisory
https://github.com/mercurius-js/mercurius/security/advisories/GHSA-273r-rm8g-7f3xPatch, Third Party Advisory

Timeline

Published: Dec 13, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-43801?

How severe is CVE-2021-43801?

CVE-2021-43801 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 1.52% probability of exploitation in the next 30 days.

How do I fix CVE-2021-43801?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-43801?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST