CyberSecBulletin
CVE-2026-75021NVD status: Awaiting Analysis

fastify-cli: Binding to an Unrestricted IP Address

Published Updated By the CyberSecBulletin desk

CVE-2026-75021 is a high-severity binding to an unrestricted IP address vulnerability in fastify-cli, with a CVSS 3.1 base score of 8.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 8.0.1 as the first without the flaw, so updating fastify-cli to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.7% chance of exploitation within 30 days, higher than 54% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update fastify-cli to 8.0.1 or a later version.
  2. Read the advisory on cna.openjsf.org for workarounds and exact fixed builds.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
Fastify-clifastify-cli1.5.0 up to, but not including, 8.0.18.0.1

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
HighSuccess depends on conditions outside the attacker's control.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA.

Official description

fastify-cli starts the Node.js Inspector when a debug flag is used, but it ignores the explicit bind address the user supplies and binds the Inspector to a broadly reachable address instead of the intended loopback. As a result the debugging interface can be exposed beyond the local machine, and because the Inspector protocol allows arbitrary code evaluation, a remote party that reaches it can achieve remote code execution on the developer's machine. This affects fastify-cli from 1.5.0 up to 8.0.1. Users should upgrade to fastify-cli 8.0.1, which honors the configured Inspector bind address.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Binding to an Unrestricted IP Address

The product assigns the address 0.0.0.0 for a database server, a cloud service/instance, or any computing resource that communicates remotely.

How developers prevent this class of flaw

  • Assign IP addresses that are not 0.0.0.0.
  • Unwanted connections to the configured server may be denied through a firewall or other packet filtering measures.

More Binding to an Unrestricted IP Address vulnerabilities (CWE-1327)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).

References

Recent Binding to an Unrestricted IP Address vulnerabilities

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