CVE-2021-21727: ZTE Zxhn f623 Firmware

High severity, CVSS 7.5. EPSS: 1.4% chance of exploitation in the next 30 days.

A ZTE product has a DoS vulnerability. A remote attacker can amplify traffic by sending carefully constructed IPv6 packets to the affected devices, which eventually leads to device denial of service. This affects:<ZXHN F623><All versions up to V6.0.0P3T33>

Affected products

• ZTE Zxhn f623 Firmware: before 6.0.0p3t34 (fixed in 6.0.0p3t34)

Published 2021-03-29. Last modified 2026-06-17.