CVE-2021-43662Public exploit

Service interruption via unbounded configuration-file appends

Published Mar 30, 2022 · Updated Aug 4, 2024

Resource exhaustion in TOTOLINK EX300_v2 and A720R firmware allows attackers on an adjacent network to interrupt service. Each ExportSettings.sh request appends the device CSID to /var/config.dat without truncation, a size limit, or request throttling. Unauthenticated access is sufficient to repeat the request until storage exhaustion places the web service or device in a denial-of-service condition.

CVSS severity6.5
Medium
EPSS probability0.55%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in TOTOLINK EX300_v2 and A720R firmware allows attackers on an adjacent network to interrupt service. Each ExportSettings.sh request appends the device CSID to /var/config.dat without truncation, a size limit, or request throttling. Unauthenticated access is sufficient to repeat the request until storage exhaustion places the web service or device in a denial-of-service condition.

The record

CVE
CVE-2021-43662
Published
Mar 30, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-770, T1499.001
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 30, 2022CVE 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 vectoradjacent
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.5NIST NVDCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.3NIST NVDAV:A/AC:L/Au:N/C:N/I:N/A:P

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)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1499.001Endpoint Denial of Service: OS Exhaustion Flood

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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