Raw vector
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HSummary
CVE-2026-21638 is a high-severity Command Injection (CWE-77) vulnerability in Ui Ubb-Xg Firmware. Its CVSS base score is 8.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Command and Scripting Interpreter (T1059); ranked at the 33th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-21638 is a remote code execution (RCE) vulnerability in the airMAX Wireless Protocol, affecting Ubiquiti networking products including UBB-XG (version 1.2.2 and earlier), UDB-Pro/UDB-Pro-Sector (version 1.4.1 and earlier), and UBB (version 3.1.5 and earlier). Published on January 8, 2026, it carries a CVSS v3.1 base score of 8.8 (AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H) and is associated with CWE-77 (Command Injection).
A malicious actor within Wi-Fi range of an affected device can exploit the vulnerability over the adjacent network with low complexity, no privileges, and no user interaction required. Successful exploitation enables arbitrary code execution on the device, granting high impacts to confidentiality, integrity, and availability.
Ubiquiti's security advisory recommends mitigation by updating affected products to patched versions: UBB-XG to 1.2.3 or later, UDB-Pro/UDB-Pro-Sector to 1.4.2 or later, and UBB to 3.1.7 or later. Additional details are available at https://community.ui.com/releases/Security-Advisory-Bulletin-060-060/cde18da7-2bc4-41bb-a9cc-48a4a4c479c1.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-1491
Vulnerability Data
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…
more
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.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
—
—
—
V1.2.3V1.2.5V1.2.8V1.2.9
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation can discover command-construction flaws before deployment.
Input validation directly stops construction of commands from untrusted data containing special elements.
Secure engineering principles include proper neutralization and safe command construction practices.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly require input validation and neutralization that prevent command injection.
Runtime monitoring of software and data can detect anomalous command execution resulting from injection.
Identifying recorded vulnerabilities enables remediation of command-injection flaws before exploitation.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Secure coding standards require proper escaping and parameterization of commands, directly eliminating CWE-77.
Security testing in development catches command-injection vulnerabilities before release.
Secure development life cycle mandates input validation and command construction practices that directly prevent command injection.
Application security requirements explicitly call for controls against injection flaws including command injection.
Secure architecture principles reduce the attack surface but do not prescribe the specific neutralization techniques needed.
Environment separation limits the blast radius of an exploited command injection but does not prevent the flaw itself.