CVE-2021-43801Public exploitNetwork attack vector

Denial of service via undefined error context

Published Dec 13, 2021 · Updated Aug 4, 2024

Denial of service in Mercurius 8.10.0 through 8.11.1 allows remote attackers to crash GraphQL request handling with malformed JSON. The default error handler passes an undefined request context to defaultErrorFormatter, which dereferences reply and throws an uncaught TypeError. Unauthenticated access to /graphql is sufficient; deployments with a custom error handler do not expose this path.

CVSS severity7.5
High
EPSS probability1.52%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Mercurius 8.10.0 through 8.11.1 allows remote attackers to crash GraphQL request handling with malformed JSON. The default error handler passes an undefined request context to defaultErrorFormatter, which dereferences reply and throws an uncaught TypeError. Unauthenticated access to /graphql is sufficient; deployments with a custom error handler do not expose this path.

The record

CVE
CVE-2021-43801
Published
Dec 13, 2021
Updated
Aug 4, 2024
Vendor
mercurius-js
Product
Mercurius
Classifications
CWE-248, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 13, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 8.10.0, < 8.11.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

mercurius-js · Mercuriusversion=>= 8.10.0, < 8.11.2

Published CVSS scores

7.5GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.0NVDAV:N/AC:L/Au:N/C:N/I:N/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-248Uncaught Exception
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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