CVE-2021-29294Network attack vector

Unauthenticated service interruption via HNAP null dereference

Published Aug 10, 2021 · Updated Aug 3, 2024

Null pointer dereference in D-Link DSL-2740R UK_1.01 allows remote attackers to interrupt service via a crafted HNAP POST request. The /userfs/bin/boa send_hnap_unauthorized function dereferences a null pointer while processing a crafted POST request to /HNAP1/. The endpoint is reachable without authentication, and the published assessment limits the consequence to loss of availability.

CVSS severity7.5
High
EPSS probability1.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Null pointer dereference in D-Link DSL-2740R UK_1.01 allows remote attackers to interrupt service via a crafted HNAP POST request. The /userfs/bin/boa send_hnap_unauthorized function dereferences a null pointer while processing a crafted POST request to /HNAP1/. The endpoint is reachable without authentication, and the published assessment limits the consequence to loss of availability.

The record

CVE
CVE-2021-29294
Published
Aug 10, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-476, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 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

5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1499.004Application or System Exploitation

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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