CVE-2021-21739

Severity: medium (CVSS 4.6 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-08-05 · updated 2026-06-17
Weakness: CWE-345

Description

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

<ZXCTN 6120H>: 5.10.00b24

References

https://support.zte.com.cn/support/news/LoopholeInfoDetail.aspx?newsId=1017024
https://support.zte.com.cn/support/news/LoopholeInfoDetail.aspx?newsId=1017024

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