CVE-2026-77546 in UniFi Access Application
Summary
by MITRE • 08/26/2026
A malicious actor with access to the network and low privileges could exploit an Improper Input Validation vulnerability found in UniFi Access Application to execute a Command Injection on the host device.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 08/26/2026
The identified security flaw resides within the UniFi Access Application, specifically manifesting as an improper input validation mechanism that facilitates command injection attacks. This vulnerability allows for arbitrary code execution on the underlying operating system of the host device where the application is installed. The core technical deficiency lies in the failure to adequately sanitize or validate user-supplied data before it is processed by internal system commands. When a malicious actor interacts with specific endpoints or features within the UniFi Access Application, they can inject shell metacharacters and command sequences into input fields that are subsequently passed to the operating system's command interpreter without proper escaping or filtering. This lack of rigorous validation enables the attacker to break out of the intended application context and execute arbitrary commands with the privileges granted to the service account running the UniFi Access Application process.
The operational impact of this vulnerability is severe, as it effectively compromises the integrity and confidentiality of the host system. An adversary who gains access to the network and possesses low-level user credentials can leverage this flaw to escalate their privilege level significantly. By executing commands on the host device, the attacker may install backdoors, exfiltrate sensitive data stored locally, modify configuration files to maintain persistence, or use the compromised host as a pivot point for further lateral movement within the enterprise network. This transforms what might appear to be a minor application-level issue into a critical infrastructure risk, potentially leading to full system compromise and disruption of access control services managed by UniFi Access.
From a classification perspective, this vulnerability aligns with CWE-78, which defines Improper Neutralization of Special Elements used in an OS Command commonly known as OS Command Injection. The attack vector is categorized under ATT&CK technique T1059, specifically subtechnique T1059.004 for Command and Scripting Interpreter abuse. This classification highlights the mechanism by which attackers utilize built-in system interpreters to execute malicious instructions, bypassing application-level security controls through input manipulation rather than exploiting complex binary vulnerabilities or memory corruption issues.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. The primary defense is for administrators to apply the latest software patches provided by Ubiquiti Inc., which address the specific input validation gaps in the UniFi Access Application codebase. In environments where patching cannot be immediately implemented, network segmentation should be enforced to restrict access to the affected application from untrusted or low-privilege networks. Additionally, implementing strict web application firewalls with rules designed to detect and block common command injection patterns can provide a layer of defense in depth. Developers must also adopt secure coding practices that emphasize parameterized commands and rigorous input sanitization protocols for all future updates to prevent recurrence of similar flaws.