Improper access control in Fastify-reply-from - CVE-2021-21321
Published: February 23, 2021 / Updated: July 20, 2026
Vulnerability identifier: #VU138404
CSH Severity: High
CVSS v4 BT: 8 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Amber]
CVE-ID: CVE-2021-21321
CWE-ID: CWE-284
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to access unintended proxied backend resources and disclose or modify sensitive information.
The vulnerability exists due to improper access control in the prefix handling logic of fastify-reply-from when processing a specially crafted URL. A remote attacker can send a specially crafted request to access unintended proxied backend resources and disclose or modify sensitive information.
Affected software
Fastify-reply-from
Red Hat Advanced Cluster Management for Kubernetes
Red Hat Advanced Cluster Management for Kubernetes
How to mitigate CVE-2021-21321
Install security update from vendor's website.
Fastify-reply-from - update to 4.0.2
Red Hat Advanced Cluster Management for Kubernetes - update to 2.2.2
Red Hat Advanced Cluster Management for Kubernetes - update to 2.2.2