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CVE-2021-21321

10.0 · CRITICAL

fastify-reply-from is an npm package which is a fastify plugin to forward the current http request to another server.

Published Mar 2, 2021CWE-20EPSS 1.82%

Overview

CVE-2021-21321 is a critical-severity vulnerability. It was published on March 2, 2021 and has a CVSS 3.1 base score of 10.0 (CRITICAL).

This vulnerability has a CVSS 3.1 base score of 10.0, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

fastify-reply-from is an npm package which is a fastify plugin to forward the current http request to another server. In fastify-reply-from before version 4.0.2, by crafting a specific URL, it is possible to escape the prefix of the proxied backend service. If the base url of the proxied server is "/pub/", a user expect that accessing "/priv" on the target service would not be possible. In affected versions, it is possible. This is fixed in version 4.0.2.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/fastify/fastify-reply-from/commit/dea227dda606900cc01870d08541b4dcc69d3889GitHubgithub.com/fastify/fastify-reply-from/security/advisories/GHSA-qmw8-3v4g-gwj4Refwww.npmjs.com/package/fastify-reply-fromGitHubgithub.com/fastify/fastify-reply-from/commit/dea227dda606900cc01870d08541b4dcc69d3889GitHubgithub.com/fastify/fastify-reply-from/security/advisories/GHSA-qmw8-3v4g-gwj4Refwww.npmjs.com/package/fastify-reply-from

How CyberStrike helps

Frequently asked questions

What is CVE-2021-21321?

CVE-2021-21321 is a critical-severity vulnerability. It was published on March 2, 2021 and has a CVSS 3.1 base score of 10.0 (CRITICAL).

How severe is CVE-2021-21321?

This vulnerability has a CVSS 3.1 base score of 10.0, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2021-21321?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2021-21321?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-21321 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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