CVE-2026-62820: Concurrent execution using shared resource with improper synchronization ('race condition') in Windows DNS all
50
This month
HIGH 8.1REMOTEWATCHLISTUPGRADEUPGRADEUPGRADE
CVE-2026-62820 is a high-severity flaw (CVSS 8.1) affecting windows 10 1607, windows 10 1809, windows server 2016. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows DNS allows an unauthorized attacker to execute code over a network.
Last updated 2026-09-02 · 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
microsoft windows 10 1607 UPGRADE
Affected: < 10.0.14393.9418
Fixed in: 10.0.14393.9418
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.
microsoft windows 10 1809 UPGRADE
Affected: < 10.0.17763.9121
Fixed in: 10.0.17763.9121
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.
microsoft windows server 2016 UPGRADE
Affected: < 10.0.14393.9418
Fixed in: 10.0.14393.9418
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.
microsoft windows server 2019 UPGRADE
Affected: < 10.0.17763.9121
Fixed in: 10.0.17763.9121
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.
microsoft windows server 2022 UPGRADE
Affected: < 10.0.20348.5440
Fixed in: 10.0.20348.5440
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.
microsoft windows server 2025 UPGRADE
Affected: < 10.0.26100.33222
Fixed in: 10.0.26100.33222
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-2026-62820?
windows 10 1607: upgrade to 10.0.14393.9418; windows 10 1809: upgrade to 10.0.17763.9121; windows server 2016: upgrade to 10.0.14393.9418. Exact commands for each OS are on this page.
Is CVE-2026-62820 being exploited?
CVE-2026-62820 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-2026-62820 affect?
CVE-2026-62820 affects windows 10 1607, windows 10 1809, windows server 2016. Severity is high (CVSS 8.1). Concurrent execution using shared resource with improper synchronization ('race condition') in Windows DNS allows an unauthorized attacker to execute code over a network.
How urgent is CVE-2026-62820?
Priority 50/100. High severity; Remotely exploitable, no login, no user action; On your watchlist
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