CVE-2021-37273Network attack vector

Unauthenticated service interruption via repeated device restarts

Published Sep 28, 2021 · Updated Aug 4, 2024

Denial of service in China Telecom EPON Tianyi Gateway ZXHN F450 firmware 3.0 allows remote attackers to repeatedly restart the device. Public records do not disclose which network-facing component or input-handling operation triggers the restart. Network reachability without authentication is sufficient, and repeated restarts interrupt gateway connectivity.

CVSS severity7.5
High
EPSS probability0.98%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in China Telecom EPON Tianyi Gateway ZXHN F450 firmware 3.0 allows remote attackers to repeatedly restart the device. Public records do not disclose which network-facing component or input-handling operation triggers the restart. Network reachability without authentication is sufficient, and repeated restarts interrupt gateway connectivity.

The record

CVE
CVE-2021-37273
Published
Sep 28, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
T1529
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 28, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.8NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:C

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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 exploitUnconfirmed

Weakness, pattern, technique

T1529System Shutdown/Reboot

Public exploit references

No public exploit references are available in this record.

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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