CVE-2021-21739: ZTE Zxctn 6120h Firmware

Medium severity, CVSS 4.6. EPSS: 0.2% chance of exploitation in the next 30 days.

A ZTE's product of the transport network access layer has a security vulnerability. Because the system does not sufficiently verify the data reliability, attackers could replace an authenticated optical module on the equipment with an unauthenticated one, bypassing system authentication and detection, thus affecting signal transmission. This affects: <ZXCTN 6120H><V5.10.00B24>

Affected products

• ZTE Zxctn 6120h Firmware: version 5.10.00b24 only

Published 2021-08-05. Last modified 2026-06-17.