CVE-2026-77554 in UniFi Talk Application
Summary
by MITRE • 08/26/2026
A malicious actor with access to the network could exploit an Improper Input Validation vulnerability found in UniFi Talk Application to execute a Command Injection on the host device.
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Analysis
by VulDB Data Team • 08/26/2026
The discovery of a command injection vulnerability within the UniFi Talk application represents a significant security risk for organizations relying on this unified communications platform. This flaw stems from improper input validation, specifically where user-supplied data is not adequately sanitized before being processed by underlying system commands or scripts. In typical software architecture, applications often interact with operating system-level functions to perform tasks such as file manipulation, network configuration, or process management. When these interactions rely on dynamic command construction without rigorous checks against malicious payloads, an attacker can inject arbitrary shell commands into the execution stream. The vulnerability allows a remote actor who has access to the local network segment where UniFi Talk is deployed to exploit this weakness, potentially gaining unauthorized control over the host device running the application.
From a technical perspective, improper input validation vulnerabilities are categorized under CWE-20 in the Common Weakness Enumeration standard. This classification highlights failures in checking or filtering user inputs for correctness and safety before processing them. In the context of command injection, which is further detailed as CWE-78, the specific failure involves the application passing unsanitized data to a system shell interpreter such as /bin/sh or cmd.exe. If an attacker can control any part of this input string, they may append additional commands using delimiters like semicolons, ampersands, or pipes. This capability effectively bypasses intended security boundaries, allowing the execution of arbitrary code with the privileges associated with the UniFi Talk process. Such a scenario is particularly dangerous if the application runs with elevated permissions, such as root on Linux-based systems or Administrator rights on Windows environments, thereby amplifying the potential impact significantly.
The operational impact of this vulnerability extends beyond simple data exposure. Successful exploitation could lead to full system compromise, where an attacker establishes persistent access through backdoors, modifies configuration files to redirect traffic, or uses the compromised host as a pivot point for lateral movement within the corporate network. This aligns with several tactics in the MITRE ATT&CK framework, including Initial Access via valid accounts if authentication is bypassed, and Execution techniques such as Command and Scripting Interpreter abuse. Furthermore, depending on the specific implementation details of how commands are constructed, this could also facilitate Privilege Escalation or Defense Evasion by manipulating system logs or security tools to hide malicious activities. The ability to execute arbitrary code means that sensitive data stored locally on the device, including call records, user credentials, and internal network topology information, becomes accessible to unauthorized parties.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. The primary defense is for vendors to release a patched version of UniFi Talk that implements strict input validation mechanisms. This includes whitelisting allowed characters, using parameterized commands instead of string concatenation when invoking system processes, and employing sandboxing techniques to limit the privileges of the application process. Organizations should immediately apply any available updates provided by Ubiquiti Inc., the developer of UniFi products. In addition to patching, network segmentation plays a critical role in reducing exposure. By isolating VoIP infrastructure from general corporate networks using VLANs or firewalls, administrators can restrict access to only those systems that strictly require communication with the UniFi Talk application. Monitoring network traffic for anomalous patterns related to command execution or unusual outbound connections can also aid in early detection of exploitation attempts while patches are being deployed.