CVE-2024-40493Public exploitNetwork attack vector

Client crash via null blockwise payload dereference

Published Oct 22, 2024 · Updated Oct 23, 2024

Null pointer dereference in FreeCoAP 1.0 allows remote attackers to crash a CoAP client via a crafted blockwise response. coap_client_exchange_blockwise2 passes the null result of coap_msg_get_payload(resp) to memcpy as its source buffer. The target must initiate a blockwise exchange with an attacker-controlled CoAP peer; the demonstrated consequence is a client crash.

CVSS severity9.8
Critical
EPSS probability0.78%
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 FreeCoAP 1.0 allows remote attackers to crash a CoAP client via a crafted blockwise response. coap_client_exchange_blockwise2 passes the null result of coap_msg_get_payload(resp) to memcpy as its source buffer. The target must initiate a blockwise exchange with an attacker-controlled CoAP peer; the demonstrated consequence is a client crash.

The record

CVE
CVE-2024-40493
Published
Oct 22, 2024
Updated
Oct 23, 2024
Vendor
Keith Cullen
Product
FreeCoAP
Classifications
CWE-476, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 22, 2024CVE publishedPublication date reported by the CVE source.
  2. Oct 23, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Keith Cullen · FreeCoAPversion=1.0

Published CVSS scores

5.3CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 exploitPublished

Weakness, pattern, technique

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

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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