CVE-2021-43801
Uncaught Exception in mercurius
Mercurius is a GraphQL adapter for Fastify. Any users from [email protected] 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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
Uncaught Exception in mercurius
Mercurius is a GraphQL adapter for Fastify. Any users from [email protected] 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.
- Record
CVE-2021-43801- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-754
- Updated
- 2026-11-02
EUVDEUVD-2021-2420
Mercurius is a GraphQL adapter for Fastify. Any users from [email protected] 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.
- Record
EUVD-2021-2420- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-273r-rm8g-7f3x
Uncaught Exception in mercurius
Impact
Any users from [email protected] 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.
Patches
The vulnerability has been fixed in https://github.com/mercurius-js/mercurius/pull/678 and shipped as v8.11.2.
Workarounds
Use a custom error handler.
References
See https://github.com/mercurius-js/mercurius/issues/677
For more information
If you have any questions or comments about this advisory:
- Open an issue in https://github.com/mercurius-js/mercurius
- Email us at [email protected]
- Record
GHSA-273r-rm8g-7f3x- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-754
- Updated
- 2026-11-02
NVD
Mercurius is a GraphQL adapter for Fastify. Any users from [email protected] 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.
- Record
CVE-2021-43801- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - CVSS 2.0
- 5.0 Medium
AV:N/AC:L/Au:N/C:N/I:N/A:P - Weakness
- CWE-754
- Updated
- 2026-11-02
OSV
Mercurius is a GraphQL adapter for Fastify. Any users from [email protected] 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.
- Record
CVE-2021-43801- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVGHSA-273r-rm8g-7f3x
Uncaught Exception in mercurius
Impact
Any users from [email protected] 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.
Patches
The vulnerability has been fixed in https://github.com/mercurius-js/mercurius/pull/678 and shipped as v8.11.2.
Workarounds
Use a custom error handler.
References
See https://github.com/mercurius-js/mercurius/issues/677
For more information
If you have any questions or comments about this advisory:
- Open an issue in https://github.com/mercurius-js/mercurius
- Email us at [email protected]
- Record
GHSA-273r-rm8g-7f3x- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-754
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
mercuriusnpm |
8.10.0 up to 8.11.2 | 8.11.2 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-43801 is a high vulnerability (CVSS 7.5) in Mercurius-js Mercurius, published December 13, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.57%, the 75th percentile. Fixed in mercurius 8.11.2.
References
github.com/mercurius-js/mercurius/security/advisories/GHSA-273r-rm8g-7f3x
nvd.nist.gov/vuln/detail/CVE-2021-43801