CVE-2021-27172Public exploitNetwork attack vector

Root shell access via hardcoded Telnet password

Published Feb 10, 2021 · Updated Aug 3, 2024

Hardcoded credentials in FiberHome HG6245D firmware through RP2613 allow remote attackers to obtain a root shell through Telnet. The /etc/init.d/system-config.sh script writes a fixed DES password hash for root into /etc/passwd, making the root password identical across affected devices. The Linux Telnet server is disabled by default, but another exposed device function can start it, after which the shared credential grants unauthenticated root access.

CVSS severity9.8
Critical
EPSS probability19.84%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Hardcoded credentials in FiberHome HG6245D firmware through RP2613 allow remote attackers to obtain a root shell through Telnet. The /etc/init.d/system-config.sh script writes a fixed DES password hash for root into /etc/passwd, making the root password identical across affected devices. The Linux Telnet server is disabled by default, but another exposed device function can start it, after which the shared credential grants unauthenticated root access.

The record

CVE
CVE-2021-27172
Published
Feb 10, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-798, T1078
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 10, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.8NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
5.0NVDAV:N/AC:L/Au:N/C:P/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-798Use of Hard-coded Credentials
T1078Valid Accounts

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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