CVE-2021-20595Network attack vector

Information disclosure and DoS via XXE

Published Jul 13, 2021 · Updated Aug 3, 2024

Improper XML entity handling in Mitsubishi Electric air conditioning systems allows remote unauthenticated attackers to disclose data or cause DoS. Controller packet parsers fail to restrict XML external entity references, allowing crafted packets to resolve entities against system data. Exploitation requires network reachability; systems exposed directly without the vendor-recommended VPN or in-building isolation can be affected.

CVSS severity9.3
Critical
EPSS probability1.78%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper XML entity handling in Mitsubishi Electric air conditioning systems allows remote unauthenticated attackers to disclose data or cause DoS. Controller packet parsers fail to restrict XML external entity references, allowing crafted packets to resolve entities against system data. Exploitation requires network reachability; systems exposed directly without the vendor-recommended VPN or in-building isolation can be affected.

The record

CVE
CVE-2021-20595
Published
Jul 13, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-611, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 13, 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

8.5NVDAV:N/AC:L/Au:N/C:P/I:N/A:C
8.2NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
9.3Mitsubishi Electric CorporationCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/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.

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-611Improper Restriction of XML External Entity Reference
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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