UniFi OS Server - RCE (CVE-2026-34910)

CVE-2026-34910 is a critical improper input validation vulnerability affecting Ubiquiti UniFi OS Server and numerous UniFi OS devices, including UDM, UNVR, UNAS, and UCG models. A network-accessible attacker can exploit this flaw without authentication or user interaction to inject and execute arbitrary commands, potentially achieving remote code execution and compromising the confidentiality, integrity, and availability of affected systems.

CrowdSec has been tracking this vulnerability and its exploits since 29th of August 2026.

According to CrowdSec data, while opportunistic exploitation dominates, a portion of threat actors trying to exploit CVE-2026-34910 apply basic targeting methods such as port or service detection. This indicates emerging patterns of selective targeting. Telemetry from the CrowdSec network also shows that exploitation activity for CVE-2026-34910 remains steady week-over-week. Attack volumes are consistent with long-term trends, indicating sustained interest from threat actors. CVE-2026-34910 continues to be an active part of the threat landscape and will likely remain this way for the forseeable future.

Attackers target the /api/auth/validate-sso/..%2f..%2f..%2fproxy/users/api/v2/ucs/update/latest_package endpoint, using encoded path traversal to reach the update API. The pkg_name parameter is injected with shell commands such as nslookup, enabling unauthenticated remote command execution and out-of-band DNS callbacks.