CVE-2020-5544Network attack vector

Network disruption via crafted TCP packet null dereference

Published Mar 16, 2020 · Updated Aug 4, 2024

Null pointer dereference in MELQIC IU1-1M20-D firmware 1.0.7 and earlier allows remote attackers to disrupt networking via crafted TCP packets. The firmware's TCP function dereferences a null pointer while processing a specially crafted packet; no finer code-level locus is public. No authentication or user interaction is required, and exploitation can stop network functions or execute malware on the appliance.

CVSS severity9.8
Critical
EPSS probability2.42%
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 MELQIC IU1-1M20-D firmware 1.0.7 and earlier allows remote attackers to disrupt networking via crafted TCP packets. The firmware's TCP function dereferences a null pointer while processing a specially crafted packet; no finer code-level locus is public. No authentication or user interaction is required, and exploitation can stop network functions or execute malware on the appliance.

The record

CVE
CVE-2020-5544
Published
Mar 16, 2020
Updated
Aug 4, 2024
Vendor
Mitsubishi Electric Corporation
Product
MELQIC IU1 Series
Classifications
CWE-476, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 16, 2020CVE 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?

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

  1. Affected versionversion=IU1-1M20-D firmware version 1.0.7 and earlier

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mitsubishi Electric Corporation · MELQIC IU1 Seriesversion=IU1-1M20-D firmware version 1.0.7 and earlier

Published CVSS scores

7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
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.

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

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 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
T1190Exploit Public-Facing Application

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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