Home/CVE/A malicious actor in Wi-Fi range of the affected product could leverage a vulnerability in the airMAX Wireless Protocol
CVE
CVE-2026-21639
A malicious actor in Wi-Fi range of the affected product could leverage a vulnerability in the airMAX Wireless Protocol
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.
MEDIUM · CVSS 5.4
EPSS 0.00033
Monitor
- No active-exploitation, high-EPSS, or public-exploit signals - routine patching cadence
Sigma rules0
YARA rules0
Look this up elsewhere - one-click external pivots
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How to read a CVE - triage first, then detect and patch
This page is every public fact about CVE-2026-21639, cross-linked. Its job is to answer one question fast - does this need my attention now? - and then hand you the two things you do about it. Here is how an analyst reads it.
Triage: should I act now? Four signals, and they are not interchangeable:
CVSSseverity - how bad it is IF exploited, 0-10. A high CVSS alone is not urgency; a flaw can be a perfect 10 and never actually be attacked.
EPSSprobability - a model’s estimate of the chance it is exploited in the next 30 days, 0-1. This is the “will it actually happen” signal.
CISA KEVconfirmed - it is being exploited in the wild right now. The strongest signal on the page; KEV beats any score.
Weaponisedavailability - public exploits / PoCs, and especially Metasploit modules rated Excellent / Great. Reliable, packaged exploit code means low-skill attackers can use it today.
How they combine: KEV, or a dependable Metasploit module, means patch now regardless of CVSS. High CVSS + low EPSS + no exploit is real but not an emergency - schedule it. Low CVSS but KEV-listed still gets patched now. The verdict above already weighed these for you; this is how it got there.
Then what - two workflows:
Detectwhen you cannot patch today, follow this CVE to the ATT&CK techniques it enables, then Build a SIEM detection (the green button) - author a rule, test it in Atomic, deploy it. That buys visibility while the patch waits.
PatchAffected products / packages tell you if you are exposed; Fixed versions by distribution and Vendor advisories give the exact version that closes it.
Reading order for the panels below: verdict + badges, then Public exploits / Metasploit (is it weaponised), then ATT&CK techniques + Sigma / IDS rules (can I detect it), then Affected products / packages + Fixed versions (am I exposed, what patches it), then Threat actors / IOCs (who uses it), then Scoring & timeline / references (the evidence).
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ATT&CK techniques
1Techniques this CVE enables - linked via CWECAPECATT&CK. High◆ = named directly in ATT&CK or Nuclei templates.
▤ Build a SIEM detection for these techniques▤
CAPEC attack patterns
8Attack patterns this CVE enables - the bridge from weakness to ATT&CK technique.
CAPEC-CAPEC-136 · LDAP Injection CAPEC-CAPEC-15 · Command Delimiters CAPEC-CAPEC-183 · IMAP/SMTP Command Injection CAPEC-CAPEC-248 · Command Injection CAPEC-CAPEC-40 · Manipulating Writeable Terminal Devices CAPEC-CAPEC-43 · Exploiting Multiple Input Interpretation Layers CAPEC-CAPEC-75 · Manipulating Writeable Configuration Files CAPEC-CAPEC-76 · Manipulating Web Input to File System Calls
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Weakness Classification
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Affected Products & Versions
4ui airmax ac firmware< 8.7.21
ui airmax m firmware< 6.3.24
ui airfiber af60-xg firmware< 1.2.3
ui airfiber af60 firmware< 2.6.8
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Scoring & Timeline
5.4
MEDIUM · CVSS v3.1 · [email protected]
Attack Vector
Network
Adjacent
Local
Physical
Attack Complexity
Low
High
Privileges Required
None
Low
High
User Interaction
None
Required
Scope
Unchanged
Changed
Confidentiality
None
Low
High
Integrity
None
Low
High
Availability
None
Low
High
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
no
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
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References & Sources
1Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.