Impact

This is a bypass of CVE-2020-8136 (https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-8136).
By providing a name=constructor property it is still possible to crash the application.
The original fix only checks for the key __proto__ (fastify/fastify-multipart#116).

All users are recommended to upgrade

Patches

v5.3.1 includes a patch

Workarounds

No workarounds are possible.

References

Read up https://www.fastify.io/docs/latest/Guides/Prototype-Poisoning/

For more information

If you have any questions or comments about this advisory:

• Open an issue in https://github.com/fastify/fastify-multipart
• Email us at [email protected]

References

• GHSA-qh73-qc3p-rjv2
• fastify/fastify-multipart#116
• fastify/fastify-multipart@a70dc70
• https://github.com/fastify/fastify-multipart/releases/tag/v5.3.1
• https://snyk.io/vuln/SNYK-JS-FASTIFYMULTIPART-2395480
• https://www.fastify.io/docs/latest/Guides/Prototype-Poisoning/
• https://nvd.nist.gov/vuln/detail/CVE-2021-23597