CVE-2021-20595: Improper Restriction of XML External Entity Reference vulnerability in Mitsubishi Electric Air Conditioning Sy
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HIGH 8.2REMOTEUPGRADEUPGRADEUPGRADE
CVE-2021-20595 is a high-severity flaw (CVSS 8.2) affecting g-50a firmware, gb-50a firmware, ag-150a-a firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
Improper Restriction of XML External Entity Reference vulnerability in Mitsubishi Electric Air Conditioning System/Centralized Controllers (G-50A Ver.3.35 and prior, GB-50A Ver.3.35 and prior, GB-24A Ver.9.11 and prior, AG-150A-A Ver.3.20 and prior, AG-150A-J Ver.3.20 and prior, GB-50ADA-A Ver.3.20 and prior, GB-50ADA-J Ver.3.20 and prior, EB-50GU-A Ver 7.09 and prior, EB-50GU-J Ver 7.09 and prior, AE-200A Ver 7.93 and prior, AE-200E Ver 7.93 and
Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
Published CVE record published
Updated Record last modified
mitsubishi g-50a firmware UPGRADE
Affected: >= 2.50 and <= 3.35
Fixed in: newer than 3.35
Safe to downgrade to: a release before 2.50
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
mitsubishi gb-50a firmware UPGRADE
Affected: >= 2.50 and <= 3.35
Fixed in: newer than 3.35
Safe to downgrade to: a release before 2.50
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
mitsubishi ag-150a-a firmware UPGRADE
Affected: <= 3.20
Fixed in: newer than 3.20
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
mitsubishi ag-150a-j firmware UPGRADE
Affected: <= 3.20
Fixed in: newer than 3.20
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
mitsubishi gb-50ada-a firmware UPGRADE
Affected: <= 3.20
Fixed in: newer than 3.20
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
mitsubishi gb-50ada-j firmware UPGRADE
Affected: <= 3.20
Fixed in: newer than 3.20
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
Verify at the official sourceNVD · CVE Program · Report a problem with this page Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2021-20595?
g-50a firmware: upgrade to newer than 3.35; gb-50a firmware: upgrade to newer than 3.35; ag-150a-a firmware: upgrade to newer than 3.20. Exact commands for each OS are on this page.
Is CVE-2021-20595 being exploited?
CVE-2021-20595 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2021-20595 affect?
CVE-2021-20595 affects g-50a firmware, gb-50a firmware, ag-150a-a firmware. Severity is high (CVSS 8.2). Improper Restriction of XML External Entity Reference vulnerability in Mitsubishi Electric Air Conditioning System/Centralized Controllers (G-50A Ver.3.35 and prior, GB-50A Ver.3.35 and prior, GB-24A Ver.9.11 and prior, AG-150A-A Ver.3.20 a
How urgent is CVE-2021-20595?
Priority 53/100. High severity; Remotely exploitable, no login, no user action
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