CVE-2026-34910: Ubiquiti UniFi OS Improper Input Validation Vulnerability

What it is

Ubiquiti UniFi OS contains an improper input validation vulnerability which could allow a malicious actor with access to the network to conduct command injection.

What to do

Treat this as urgent. Identify every affected system, starting with anything internet-facing, and apply the vendor fix or mitigation within days. If you cannot patch quickly, isolate or disable the affected service and watch for signs of compromise.

Priority

Act now: Patch or mitigate internet-facing systems within days.

Severity (CVSS)

10 critical

CISA assessment (SSVC)

actively exploited; attackers can automate it at scale; total control of the affected system

Exploit probability (EPSS, 30 days)

46%, higher than 98% of all CVEs

Added to CISA KEV

23 June 2026

CISA fix-by date

26 June 2026 (US federal agencies; a sensible deadline for everyone)

Ransomware use

Not known

Weakness

CWE-20

References

• NIST NVD entry
• CISA KEV entry
• community.ui.com/releases/Security-Advisory-Bulletin-064-064/84811c09-4cf4-42ab-
• www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-34910
• www.pwndefend.com/2026/06/09/cve-2026-34910-exploitation-itw-building-a-botnet-m

Sources: CISA Known Exploited Vulnerabilities · FIRST Exploit Prediction Scoring System (EPSS) · NIST National Vulnerability Database · CISA Vulnrichment (SSVC), via the CVE Program. This product uses data from the NVD API but is not endorsed or certified by the NVD. Summaries are machine-written from CISA’s description; treat the vendor’s advisory as the authority for fixes.