What is CVE-2026-77555?

CVE-2026-77555 is a high-severity vulnerability in Ubiquiti Inc Cloud Gateways, classified under Out-of-bounds Write. CVSS score: 7.5/10. Published 2026-09-22.

How severe is CVE-2026-77555?

High severity. CVSS v3 base score is 7.5 out of 10.

Buffer overflow in Ubiquiti Inc Cloud Gateways

CVE-2026-77555

A malicious actor with access to the network could exploit an Out-of-bounds Write vulnerability found in certain UniFi gateway devices to execute a Denial of Service (DoS) attack on the device.

Vulnerability class: Buffer Overflow

Published 2026-09-22 · last modified 2026-09-22.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

References

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Frequently asked questions

What is CVE-2026-77555?: CVE-2026-77555 is a high-severity vulnerability in Ubiquiti Inc Cloud Gateways, classified under Out-of-bounds Write. CVSS score: 7.5/10. Published 2026-09-22.
How severe is CVE-2026-77555?: High severity. CVSS v3 base score is 7.5 out of 10.