Security readout for executives and security teams
Plain-English summary
An attacker within Wi-Fi range could exploit the airMAX wireless protocol to run code on certain Ubiquiti wireless products. Successful exploitation could compromise data, alter device operation, or cause outages. The supplied sources do not establish affected firmware versions or confirm exploitation in the wild.
Executive priority
Treat as a high-priority wireless infrastructure issue. Promptly identify listed equipment and consult Ubiquiti's advisory, especially where compromise could disrupt critical connectivity. Immediate emergency action depends on confirmed affected firmware and operational exposure, which the supplied bundle does not resolve.
Technical view
CVE-2026-21639 is an adjacent-network RCE affecting the airMAX Wireless Protocol. Its CVSS 3.1 score is 8.8, with low complexity, no privileges, and no user interaction. CWE-120 and CWE-77 indicate memory-buffer and command-injection concerns, but the bundle provides no root-cause detail.
Likely exposure
Potential exposure is limited to listed Ubiquiti airMAX AC, airMAX M, airFiber AF60-XG, and airFiber AF60 devices reachable within radio range. The supplied version entries do not establish which firmware releases are vulnerable, so inventory comparison with current vendor guidance is necessary.
Exploitation context
The CVSS vector requires adjacent-network access, meaning an attacker must be within relevant wireless range rather than anywhere on the internet. No privileges or user interaction are required. The bundle marks this CVE as not present in KEV and provides no evidence of active exploitation.
Researcher notes
The record associates CWE-120 and CWE-77 with protocol-level RCE, but supplies no vulnerable code path, firmware boundaries, indicators, or technical remediation details. The structured affected entries show version "0" with default status "unaffected," making precise applicability unclear without the vendor bulletin.
Mitigation direction
- Review Ubiquiti Security Advisory Bulletin 061 for confirmed affected firmware and vendor remediation.
- Apply vendor-supported fixed firmware where the advisory identifies an affected deployment.
- Reduce untrusted physical and radio proximity to potentially affected equipment until remediation is confirmed.
- Prioritize externally accessible or operationally critical wireless links for assessment.
Validation and detection
- Inventory the four listed product families and record exact models and firmware versions.
- Compare each firmware version against Ubiquiti Security Advisory Bulletin 061.
- Verify remediated devices report the intended firmware after maintenance.
- Monitor affected wireless infrastructure for unexpected configuration changes, instability, or service interruption.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-120: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCWE-77: Command execution behavior lookup
Command injection weaknesses can lead defenders to review execution techniques and command interpreter telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-21639 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
2 official scoresWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H2.85.9hackeroneCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N2.82.5CISA-ADPVulnerability scoring details
Base CVSS 3.1 score
8.8HighVector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Base CVSS 3.1 score
5.4MediumVector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://community.ui.com/releases/Security-Advisory-Bulletin-061-061/1e4fe5f8-29c7-4a7d-a518-01b1537983baCVE reference, hackerone
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Improper Neutralization of Special Elements used in a Command ('Command Injection')
Improper Neutralization of Special Elements used in a Command ('Command Injection') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.