How severe is CVE-2026-21639?

CVE-2026-21639 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2026-21639 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (18th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-21639?

CVE-2026-21639 primarily affects Ui Airmax Ac Firmware. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-21639?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-21639 have an EU (EUVD) identifier?

Yes. CVE-2026-21639 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-1493.

When was CVE-2026-21639 published?

CVE-2026-21639 was published on 2026-01-08 and last updated on 2026-06-17.

CVE-2026-21639

CVE-2026-21639 is a medium-severity vulnerability in Ui Airmax Ac Firmware with a CVSS 3.x base score of 5.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-77.

Key facts

Severity: Medium (CVSS 3.x base score 5.4)
EPSS exploit prediction: 0% (18th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-1493
Weakness: CWE-77
Affected product: Ui Airmax Ac Firmware
Published: 2026-01-08
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2026-21639?: 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.
How severe is CVE-2026-21639?: CVE-2026-21639 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2026-21639 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (18th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-21639?: CVE-2026-21639 primarily affects Ui Airmax Ac Firmware. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-21639?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-21639 have an EU (EUVD) identifier?: Yes. CVE-2026-21639 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-1493.
When was CVE-2026-21639 published?: CVE-2026-21639 was published on 2026-01-08 and last updated on 2026-06-17.

References

https://community.ui.com/releases/Security-Advisory-Bulletin-061-061/1e4fe5f8-29c7-4a7d-a518-01b1537983ba

Affected products (4)

cpe:2.3:o:ui:airmax_ac_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:ui:airmax_m_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:ui:airfiber_af60-xg_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:ui:airfiber_af60_firmware:*:*:*:*:*:*:*:*

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