CVE-2021-43722Public exploitNetwork attack vector

Remote code execution via soapaction stack overflow

Published Mar 31, 2022 · Updated Aug 4, 2024

Buffer overflow in D-Link DIR-645 1.03 A1 allows remote attackers to execute code via a crafted HNAP SOAPAction header. The hnap_main function in the cgibin handler uses sprintf to copy the SOAPAction value into a stack buffer without bounding its length, allowing overwrite of adjacent stack data. Exploitation requires network access to the HNAP interface; the published CVSS assessment indicates potential confidentiality, integrity, and availability loss.

CVSS severity9.8
Critical
EPSS probability3.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Buffer overflow in D-Link DIR-645 1.03 A1 allows remote attackers to execute code via a crafted HNAP SOAPAction header. The hnap_main function in the cgibin handler uses sprintf to copy the SOAPAction value into a stack buffer without bounding its length, allowing overwrite of adjacent stack data. Exploitation requires network access to the HNAP interface; the published CVSS assessment indicates potential confidentiality, integrity, and availability loss.

The record

CVE
CVE-2021-43722
Published
Mar 31, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 31, 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 vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/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.

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 exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1190Exploit Public-Facing Application

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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