CVE-2021-21727

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-03-29 · updated 2026-06-17

Description

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

<ZXHN F623>: before 6.0.0p3t34 — fixed in 6.0.0p3t34

How to fix

Upgrade to a fixed version: <ZXHN F623> 6.0.0p3t34. Check the vendor advisory for mitigations.

References

https://support.zte.com.cn/support/news/LoopholeInfoDetail.aspx?newsId=1014744
https://support.zte.com.cn/support/news/LoopholeInfoDetail.aspx?newsId=1014744

Get alerted when CVE-2021-21727 or the next vulnerability affects your stack