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Vulnerability record · CVE-2021-27171 · published 10 February 2021

CVE-2021-27171: Fiberhome hg6245d firmware out-of-bounds write vulnerability

Fiberhome · Hg6245d Firmware

An issue was discovered on FiberHome HG6245D devices through RP2613. It is possible to start a Linux telnetd as root on port 26/tcp by using the CLI interface commands of ddd and shell (or tshell).

9.8 CVSS 3.1 Critical EPSS 18% · top 2.9% CWE-787 · Out-of-bounds write
9.8CVSS 3.1 base score, v2 10.0
18%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

An issue was discovered on FiberHome HG6245D devices through RP2613. It is possible to start a Linux telnetd as root on port 26/tcp by using the CLI interface commands of ddd and shell (or tshell).

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://pierrekim.github.io/blog/2021-01-12-fiberhome-ont-0day-vulnerabilities.html#telnet-cli-privilege-escalation ExploitThird Party Advisory
https://pierrekim.github.io/blog/2021-01-12-fiberhome-ont-0day-vulnerabilities.html#telnet-cli-privilege-escalation ExploitThird Party Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2021-27172Fiberhome hg6245d firmware hard-coded credentials vulnerabilityAn issue was discovered on FiberHome HG6245D devices through RP2613. A hardcoded GEPON password for root is defined inside /etc/init.d/system-config.…EPSS 20%9.8CVE-2021-27177Fiberhome hg6245d firmware incorrect authorization vulnerabilityAn issue was discovered on FiberHome HG6245D devices through RP2613. It is possible to bypass authentication by sending the decoded value of the Ggpo…EPSS 20%9.8CVE-2021-27158Fiberhome hg6245d firmware hard-coded credentials vulnerabilityAn issue was discovered on FiberHome HG6245D devices through RP2613. The web daemon contains the hardcoded L1vt1m4eng / 888888 credentials for an ISP.EPSS 24%9.8CVE-2021-27159Fiberhome hg6245d firmware hard-coded credentials vulnerabilityAn issue was discovered on FiberHome HG6245D devices through RP2613. The web daemon contains the hardcoded useradmin / 888888 credentials for an ISP.EPSS 24%9.8CVE-2021-27160Fiberhome hg6245d firmware hard-coded credentials vulnerabilityAn issue was discovered on FiberHome HG6245D devices through RP2613. The web daemon contains the hardcoded user / 888888 credentials for an ISP.EPSS 17%9.8CVE-2021-27161Fiberhome hg6245d firmware hard-coded credentials vulnerabilityAn issue was discovered on FiberHome HG6245D devices through RP2613. The web daemon contains the hardcoded admin / 1234 credentials for an ISP.EPSS 17%9.8CVE-2021-27162Fiberhome hg6245d firmware hard-coded credentials vulnerabilityAn issue was discovered on FiberHome HG6245D devices through RP2613. The web daemon contains the hardcoded user / tattoo@home credentials for an ISP.EPSS 27%9.8CVE-2021-27163Fiberhome hg6245d firmware hard-coded credentials vulnerabilityAn issue was discovered on FiberHome HG6245D devices through RP2613. The web daemon contains the hardcoded admin / tele1234 credentials for an ISP.EPSS 24%

Source: NIST National Vulnerability Database (record CVE-2021-27171), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.