What is CVE-2026-21638?

CVE-2026-21638 is a high-severity vulnerability in Ubiquiti Inc Ubb, classified under Command Injection. CVSS score: 8.8/10. Published 2026-01-08.

How severe is CVE-2026-21638?

High severity. CVSS v3 base score is 8.8 out of 10.

RCE in Ubiquiti Inc Ubb

CVE-2026-21638

A malicious actor in Wi-Fi range of the affected product could leverage a vulnerability in the airMAX Wireless Protocol to achieve a remote code execution (RCE) within the affected product. Affected Products: UBB-XG (Version 1.2.2 and earlier) UDB-Pro/UDB-Pro-Sector (Version 1.4.1 and earlier) UBB (Version 3.1.5 and earlier) Mitigation: Update your UBB-XG to Version 1.2.3 or later. Update your UDB-Pro/UDB-Pro-Sector to Version 1.4.2 or later. Update your UBB to Version 3.1.7 or later.

Vulnerability class: Command Injection (OS Command Injection)

EPSS: 0.004 (30.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Affected products

Ubiquiti Inc Ubb — versions 0
Ubiquiti Inc Ubb-xg — versions 0
Ubiquiti Inc Udb-pro/udb-pro-sector — versions 0
Ui Ubb
Ui Ubb_firmware
Ui Ubb-xg
Ui Ubb-xg_firmware
Ui Udb-pro
Ui Udb-pro_firmware
Ui Udb-pro-sector

Weakness classification (CWE)

CWE-77 — Command Injection

References

support@hackerone.com (Vendor Advisory)

Frequently asked questions

What is CVE-2026-21638?: CVE-2026-21638 is a high-severity vulnerability in Ubiquiti Inc Ubb, classified under Command Injection. CVSS score: 8.8/10. Published 2026-01-08.
How severe is CVE-2026-21638?: High severity. CVSS v3 base score is 8.8 out of 10.