CVE-2026-54405: UniFi Network Application DoS Vulnerability (CVSS 7.5)

Technical summary

CVE-2026-54405 is an improper input validation vulnerability (CWE-20) in the UniFi Network Application that enables network-based denial of service. The application fails to properly validate and sanitize incoming network traffic, allowing an unauthenticated attacker with network access to send malformed or oversized requests that exhaust resources or trigger unhandled exceptions. The CVSS 3.1 score of 7.5 (HIGH severity) reflects the network-adjacent attack vector, low complexity, and high availability impact, though the vulnerability does not compromise confidentiality or integrity.

Business impact

Successful exploitation disrupts UniFi Network Application availability, which typically serves as the management plane for wireless networks, switches, gateways, and other UniFi hardware. Extended downtime prevents administrators from monitoring and managing network infrastructure, potentially affecting user connectivity, security policies, and network visibility. For organizations relying on UniFi for critical site connectivity or branch office management, this could cascade into broader operational impact.

Affected systems

Ubiquiti UniFi Network Application is affected. The exact affected versions are not specified in the available advisory data; verify the vendor's security notice for the precise version range and patched releases. Deployments range from small business single-controller setups to large distributed architectures managing multiple sites.

Exploitability

Exploitation requires network-level access to the UniFi Network Application. An attacker cannot exploit this remotely from the internet without prior compromise of network perimeter controls or internal presence. The attack is trivial once network access is achieved—no authentication is required, no user interaction is needed, and exploitation is reliable. Internal threat actors, compromised endpoints, or adversaries with network lateral movement capabilities represent the primary risk.

Remediation

Patch the UniFi Network Application to a version that includes input validation hardening. Verify the specific patched version against Ubiquiti's official security advisory. Implement network segmentation to restrict access to the UniFi controller to trusted administrative networks and devices. Monitor for suspicious network traffic directed at the application port. Consider disabling remote management access if not required.

Patch guidance

Check Ubiquiti's official security advisory for the minimum patched version. UniFi Network Application updates are typically delivered through the controller's built-in update mechanism or via the UniFi dashboard. Test patches in a staging environment before production deployment, especially in environments managing critical network infrastructure. Plan updates during maintenance windows to minimize disruption if the controller requires a restart.

Detection guidance

Monitor UniFi Network Application logs for unexpected errors, crashes, or restarts coinciding with unusual network traffic patterns. Network intrusion detection systems should flag malformed or oversized packets destined for the UniFi controller management port. Watch for repeated connection attempts from internal hosts with payloads that deviate from normal UniFi API or protocol patterns. Baseline normal traffic volumes and alert on anomalies.

Why prioritize this

Although this vulnerability requires network access and is not yet tracked in CISA's Known Exploited Vulnerabilities (KEV) catalog, the combination of HIGH CVSS severity, ease of exploitation post-access, and potential for widespread disruption of network management justifies prompt patching. Internal threat actors and compromised hosts are realistic threats in most organizations. Prioritize patching if your UniFi controller is accessible from guest networks, DMZs, or less-trusted network segments.

Risk score, explained

The CVSS 3.1 base score of 7.5 reflects a network-adjacent attack surface (AV:N), low attack complexity (AC:L), no privilege requirement (PR:N), no user interaction (UI:N), and a bounded scope (S:U) with high availability impact (A:H). The absence of confidentiality and integrity impact limits the score. However, organizational risk may be higher depending on UniFi's criticality to your network operations and the quality of network segmentation protecting the controller.

Frequently asked questions