What is CVE-2021-27177?

CVE-2021-27177 is a critical-severity vulnerability in Fiberhome Hg6245d, classified under Incorrect Authorization. CVSS score: 9.8/10. Published 2021-02-10.

How severe is CVE-2021-27177?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Auth bypass in Fiberhome Hg6245d

CVE-2021-27177

An issue was discovered on FiberHome HG6245D devices through RP2613. It is possible to bypass authentication by sending the decoded value of the GgpoZWxwCmxpc3QKd2hvCg== string to the telnet server.

Vulnerability class: Broken Access Control

Published 2021-02-10 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.197 (97.3th percentile), scored 2026-09-30.

Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 97th percentile — 97.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.197 · newest: 0.197 · change: 0.000

Affected products

Weakness classification (CWE)

CWE-863 — Incorrect Authorization

References

pierrekim.github.io/blog/2021-01-12-fiberhome-ont-0day-vulnerabilities.html (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2021-27177?: CVE-2021-27177 is a critical-severity vulnerability in Fiberhome Hg6245d, classified under Incorrect Authorization. CVSS score: 9.8/10. Published 2021-02-10.
How severe is CVE-2021-27177?: Critical severity. CVSS v3 base score is 9.8 out of 10.