CVE-2026-77547 Overview
CVE-2026-77547 is a command injection vulnerability in the Ubiquiti UniFi Access Application caused by improper input validation [CWE-20]. An authenticated attacker with low privileges and network access to the affected system can inject arbitrary operating system commands that execute on the host device. Successful exploitation results in full compromise of confidentiality, integrity, and availability, with the scope extending beyond the vulnerable component. Ubiquiti disclosed the issue in Security Advisory Bulletin 067.
Critical Impact
A low-privileged network attacker can execute arbitrary commands on the UniFi Access host, leading to full device takeover and lateral movement into physical access control infrastructure.
Affected Products
- Ubiquiti UniFi Access Application
- UniFi Access host devices running the vulnerable application
- Deployments exposing the UniFi Access management interface to authenticated users
Discovery Timeline
- 2026-08-26 - CVE-2026-77547 published to NVD
- 2026-08-26 - Last updated in NVD database
Technical Details for CVE-2026-77547
Vulnerability Analysis
The vulnerability resides in the UniFi Access Application, Ubiquiti's software for managing physical access control hardware such as door readers and NFC-based entry systems. The application fails to properly validate or sanitize user-supplied input before passing it to a system command interpreter on the host device.
Because the flaw is reachable over the network and requires only low-privileged authentication, the barrier to exploitation is minimal in environments where operator or technician accounts exist. The scope change indicates that code executed through the injection escapes the security context of the UniFi Access Application and affects the underlying host operating system.
Root Cause
The root cause is improper input validation [CWE-20] on parameters that flow into an OS command execution path. Input fields intended for configuration or operational data are concatenated into shell commands without escaping shell metacharacters such as ;, |, &, and backticks. This allows an attacker to append additional commands that the host shell then executes with the privileges of the UniFi Access Application process.
Attack Vector
The attack vector is network-based. An authenticated attacker with a low-privileged account on the UniFi Access Application sends a crafted request to a vulnerable endpoint. The malicious payload embeds shell metacharacters within an otherwise valid input field. The application passes the concatenated string to the host shell, which executes attacker-controlled commands. No user interaction is required.
No public proof-of-concept exploit is available at the time of publication. Technical details are described in the Ubiquiti Security Advisory Bulletin 067.
Detection Methods for CVE-2026-77547
Indicators of Compromise
- Unexpected child processes spawned by the UniFi Access Application service, particularly shells such as sh, bash, or utilities like curl, wget, and nc.
- Outbound network connections from the UniFi Access host to unfamiliar external addresses.
- New or modified files in application working directories, cron entries, or systemd unit files created by the application user.
- HTTP requests to UniFi Access administrative endpoints containing shell metacharacters (;, |, &&, backticks, $()).
Detection Strategies
- Monitor process ancestry on UniFi Access hosts and alert when the application process spawns command interpreters or download utilities.
- Enable verbose access and audit logging on the UniFi Access Application and forward logs to a centralized analytics platform for correlation.
- Deploy network detection rules that inspect requests to UniFi Access management APIs for shell metacharacter patterns.
Monitoring Recommendations
- Continuously track authentication events for low-privileged UniFi Access accounts, focusing on unusual source IPs or off-hours activity.
- Baseline outbound traffic from access control appliances and alert on deviations that could indicate reverse shells or data staging.
- Track configuration changes to door controllers and readers that could indicate abuse following host compromise.
How to Mitigate CVE-2026-77547
Immediate Actions Required
- Apply the fixed version of the UniFi Access Application as identified in Ubiquiti Security Advisory Bulletin 067.
- Restrict network access to the UniFi Access management interface to trusted administrative networks only.
- Audit all UniFi Access user accounts and remove or rotate credentials for unused or over-privileged accounts.
- Review UniFi Access hosts for signs of prior exploitation, including unexpected processes, files, and outbound connections.
Patch Information
Ubiquiti published Security Advisory Bulletin 067 addressing this vulnerability. Administrators should consult the advisory for the specific fixed release of the UniFi Access Application and upgrade all affected deployments. Refer to the Ubiquiti Security Advisory Bulletin 067 for version details and upgrade instructions.
Workarounds
- Place UniFi Access hosts behind a firewall or VPN so the management interface is not reachable from general user networks.
- Enforce strong, unique credentials and multi-factor authentication for every account with access to the UniFi Access Application.
- Segment access control infrastructure onto a dedicated VLAN with strict egress filtering to limit post-exploitation movement.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
