CVE-2026-77553: UniFi Access Privilege Escalation Flaw

CVE-2026-77553 is a privilege escalation vulnerability in UniFi Access Application caused by improper access control. Low-privileged attackers on the network can exploit this flaw to gain elevated privileges on the host device. This article covers technical details, affected versions, impact assessment, and mitigation strategies.

CVE-2026-77553 Overview

CVE-2026-77553 is an improper access control vulnerability in the Ubiquiti UniFi Access Application. A network-adjacent attacker holding low-privilege credentials can escalate privileges on the host device running the application. The flaw is classified under CWE-284: Improper Access Control and carries a CVSS 3.1 base score of 9.9 with scope change, indicating impact beyond the vulnerable component.

Critical Impact
An authenticated low-privilege attacker on the network can gain elevated privileges on the host, compromising confidentiality, integrity, and availability of the UniFi Access deployment.

Affected Products

Ubiquiti UniFi Access Application
Refer to the UI Community Security Advisory 067 for specific affected versions
Host devices running the UniFi Access Application service

Discovery Timeline

2026-08-26 - CVE-2026-77553 published to the National Vulnerability Database
2026-08-26 - Last updated in NVD database

Technical Details for CVE-2026-77553

Vulnerability Analysis

The vulnerability resides in the access control logic of the UniFi Access Application. The application fails to correctly enforce authorization boundaries between low-privilege users and higher-privilege operations. As a result, an authenticated user with minimal permissions can invoke functionality reserved for administrative roles.

The scope change indicator in the CVSS vector shows that a successful exploit crosses trust boundaries. Compromise of the UniFi Access Application propagates to the underlying host device, expanding the blast radius beyond the application container itself.

UniFi Access controls physical door hardware, credential readers, and access logs. Privilege escalation on the host allows an attacker to manipulate door policies, disable audit logging, exfiltrate credential data, or pivot into adjacent network segments.

Root Cause

The root cause is CWE-284: Improper Access Control. The application does not adequately verify the privilege level of the requesting user before executing sensitive host-level operations. Missing or incomplete authorization checks on privileged code paths allow the escalation.

Attack Vector

Exploitation requires network access to the UniFi Access Application and valid low-privilege credentials. The attack complexity is low and no user interaction is required. An attacker sends crafted requests to the application interface to invoke privileged operations from a non-privileged context. Refer to the vendor advisory for technical specifics.

Detection Methods for CVE-2026-77553

Indicators of Compromise

Unexpected privilege changes or new administrative sessions originating from low-privilege UniFi Access accounts
Modifications to door access policies, user roles, or credential databases outside change windows
Anomalous processes or child processes spawned by the UniFi Access Application service on the host
Outbound network connections from the UniFi Access host to unfamiliar destinations

Detection Strategies

Review UniFi Access audit logs for role escalations and administrative actions correlated with low-privilege accounts
Baseline the process tree of the UniFi Access service and alert on deviations, including new binaries executed by the service account
Correlate authentication events with subsequent configuration changes to identify unauthorized privilege use

Monitoring Recommendations

Forward UniFi Access application logs and host telemetry to a centralized SIEM for retention and correlation
Monitor host-level file integrity for the UniFi Access installation directory and configuration files
Alert on new local accounts, sudoers changes, or scheduled tasks on hosts running UniFi Access

How to Mitigate CVE-2026-77553

Immediate Actions Required

Apply the security update referenced in UI Community Security Advisory 067 as soon as possible
Audit all UniFi Access user accounts and remove or disable inactive low-privilege accounts
Rotate credentials for all UniFi Access users and any service accounts used by the host
Review recent administrative actions and access policy changes for signs of exploitation

Patch Information

Ubiquiti has published remediation guidance in UI Community Security Advisory 067. Administrators should upgrade the UniFi Access Application to the fixed release identified in the advisory and validate the upgrade on all managed hosts.

Workarounds

Restrict network reachability of the UniFi Access Application to trusted management VLANs and administrator workstations
Enforce multi-factor authentication for all UniFi Access accounts to reduce the value of stolen low-privilege credentials
Segment the UniFi Access host from general-purpose networks to limit lateral movement if the host is compromised

bash

# Example: restrict UniFi Access management access with host firewall rules
# Replace 10.10.20.0/24 with your management network
iptables -A INPUT -p tcp --dport 443 -s 10.10.20.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP