CVE-2026-55116 -- CVSS 9.0 Vulnerability Briefing

CVE-2026-55116 | CVSS 9.0 (Critical) | Exploit: No known exploit

What Is It

CVE-2026-55116 is an Improper Access Control vulnerability affecting devices running Ubiquiti UniFi OS, exploitable by an attacker with network access under certain network configurations.

Technical Detail

The flaw resides in the access control logic of UniFi OS, where insufficient enforcement of authorization checks allows a network-adjacent attacker to perform unauthorized actions on affected devices. An attacker positioned on the network can craft requests that bypass intended access restrictions, potentially gaining the ability to modify device configurations, access administrative functions, or interact with protected resources without valid credentials or elevated privileges. The precise impact scope, including whether this enables full administrative takeover or partial unauthorized access, has not been fully detailed in available public disclosures at this time.

Exploitation Status

No known exploit exists for this vulnerability as of July 09, 2026. The exploit maturity is assessed at the lowest tier, indicating no public proof-of-concept code, no observed exploitation attempts, and no listing in the CISA Known Exploited Vulnerabilities catalog. This status may change given the high CVSS score of 9.0 and the broad deployment of UniFi OS devices in enterprise and prosumer environments.

Who Is Targeting This

No specific threat actor attribution at this time. Neither confirmed nor reported threat actor associations have been established for this CVE. Given the absence of observed exploitation, no campaign activity has been linked to this vulnerability.

What To Do

Organizations running UniFi OS devices should apply any available patches from Ubiquiti as a priority given the Critical severity rating. Administrators should review Ubiquiti's official security advisories and update UniFi OS to the latest patched version immediately. As an interim measure, restrict network access to UniFi OS management interfaces by placing them on isolated management VLANs and enforcing strict firewall rules to limit exposure to trusted administrative hosts only. Disable any unnecessary network services on affected devices to reduce the attack surface. Monitor device logs for anomalous access attempts or unexpected configuration changes as a detection signal while patches are being deployed.