CVE-2026-54400: A malicious actor with access to the network and high privileges could exploit an Improper Access Control vulnerability found in UniFi Access Application to escalate privileges on the host device

Synopsis

An improper access control vulnerability in the Ubiquiti UniFi Access Application allows a network-reachable attacker with high privileges to escalate those privileges on the host device. The vulnerability is reachable over the network, requires an existing high-privilege account, and needs no victim interaction to exploit. Successful exploitation gives the attacker full control over the host, including reading, modifying, and disrupting all data and services on that system. A patched-image rebuild at version 4.2.29 is available on HarborGuard for environments running an affected version.

HarborGuard Coverage

Exploit Conditions

• Network reachabilityRequired

  The attacker must reach the UniFi Access Application service over the network; it is not exploitable from a purely local or physical position.

• AuthenticationRequired

  An admin-level or otherwise high-privilege account is required before the access control flaw can be triggered.

• Victim interactionNot required

  No action from another user or administrator is needed; the attacker can trigger the exploit entirely on their own.

• Attack complexityDetail

  Exploitation is reliable and condition-free, with no race conditions or special environmental factors required.

Blast Radius

• The attacker gains elevated privileges on the host device, allowing execution of arbitrary commands as a higher-privileged user or process.
• All data accessible on the host is exposed for reading, including credentials, configuration files, and stored access-control records.
• The attacker can modify persisted configuration, user data, and access policies stored on the host.
• The attacker can crash or disable the UniFi Access Application and any co-located services on the host, disrupting physical access control operations.