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01 Record

CVE-2026-77539

A malicious actor with access to the network and high privileges could exploit an Improper Input Validation vulnerability found in UniFi OS Server to execute a Command Injection on the host device.

CriticalPUBLISHEDCNA: Ubiquiti
CNA base score9.1 CVSS v3.xCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
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02 Description

A malicious actor with access to the network and high privileges could exploit an Improper Input Validation vulnerability found in UniFi OS Server to execute a Command Injection on the host device.

03 Exploitation and scoring

Exploitation
Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.
SSVC decision
  • ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
  • AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
  • Technical ImpacttotalSuccessful exploitation gives total control of the vulnerable component.
CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.
EPSS probability
1.29% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 70.0% of scored records. A rank, not a probability.
NVD base score
9.1 (CVSS v3.x), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
NVD analysis status
Deferred. NVD last modified this record on 2026-08-28.
Red Hat severity
No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2026-08-26 09:50Z2 MO AGO
Last updated
2026-08-27 03:56Z2 MO AGO
Reserved
2026-08-20
Assigning CNA
Ubiquiti
Record state
PUBLISHED
Severity
Critical (CVSS 9.1)
CNA CVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Weaknesses
  • CWE-20Improper Input ValidationClass
Data version
5.2
Document digest
1392e080348d137e99001266853e20cd34430bae58893799f8f9c1af2261bb3a

05 Affected products

VendorProductVersionsPlatforms
Ubiquiti IncUniFi OS Server0 to < 5.1.37—

06 References