Is CVE-2026-21639 in the CISA KEV catalog?

No. CVE-2026-21639 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-21639?

CVE-2026-21639 has a CVSS v3 base score of 5.4 (MEDIUM).

What is the EPSS score for CVE-2026-21639?

CVE-2026-21639 has an EPSS score of 0.27% (18th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-21639?

Upgrade airfiber af60-xg firmware to 1.2.3 or later. Fixes are available for 4 affected products.

CVE & CISA-KEV Catalog

CVE-2026-21639

MEDIUM

5.4

CVSS v3

NVD

Description

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: airMAX AC (Version 8.7.20 and earlier) airMAX M (Version 6.3.22 and earlier) airFiber AF60-XG (Version 1.2.2 and earlier) airFiber AF60 (Version 2.6.7 and earlier) Mitigation: Update your airMAX AC to Version 8.7.21 or later. Update your airMAX M to Version 6.3.24 or later. Update your airFiber AF60-XG to Version 1.2.3 or later. Update your airFiber AF60 to Version 2.6.8 or later.

CWE-77Command Injection

How to fix

Remediation Available

airfiber af60-xg firmwareNVD

Affected:< 1.2.3Fixed in:1.2.3CVE-2026-21639derived from NVD

airfiber af60 firmwareNVD

Affected:< 2.6.8Fixed in:2.6.8CVE-2026-21639derived from NVD

airmax ac firmwareNVD

Affected:< 8.7.21Fixed in:8.7.21CVE-2026-21639derived from NVD

airmax m firmwareNVD

Affected:< 6.3.24Fixed in:6.3.24CVE-2026-21639derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorAdjacent

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityLow

IntegrityLow

AvailabilityNone

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Exploit Intelligence

0.27%probability of exploitation in 30 days

18thpercentile

Low risk: more likely to be exploited than 18% of all known CVEs.

References

Vendor Advisory1

community.ui.com

Related Vulnerabilities

Other CWE-77 (Command Injection) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-3400	Critical	10.0	100%	KEV + Ransom	-
CVE-2024-21887	Critical	9.1	100%	KEV + Ransom	-
CVE-2023-1671	Critical	9.8	100%	KEV	Fix
CVE-2023-1389	High	8.8	100%	KEV	Fix
CVE-2021-1498	Critical	9.8	100%	KEV	Fix
CVE-2012-1823	Critical	9.8	100%	KEV	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-01-14.