PatchTheCVECVE-2026-50518: Heap-based buffer overflow in Windows DHCP Server allows an unauthorized attacker to execute code over a netwo
63
This week
CRITICAL 9.8REMOTEWATCHLISTUPGRADEUPGRADEMITIGATE
CVE-2026-50518 is a critical-severity flaw (CVSS 9.8) affecting windows 10 1607, windows 10 1809, windows server 2012. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
Heap-based buffer overflow in Windows DHCP Server allows an unauthorized attacker to execute code over a network.
Why this priority
- Critical severity
- CISA SSVC: automatable with total technical impact
- Remotely exploitable, no login, no user action
- On your watchlist
A fixed release or distro patch exists.
Risk facts
| CVSS score | 9.8 (Critical) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 1.0% (top 38%) |
| CISA exploited list | No |
| Weakness | CWE-122 |
| Published | 2026-07-14 |
| Last modified | 2026-07-22 |
Publisher (CNA): Microsoft Corporation · Vendor: microsoft
Last updated 2026-07-22 · 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: < 10.0.14393.9339
Fixed in: 10.0.14393.9339
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: < 10.0.17763.9020
Fixed in: 10.0.17763.9020
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 2012 MITIGATE
Affected: all versions · r2
Fixed in: no fixed release known
Safe to downgrade to: a release before r2
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: < 10.0.14393.9339
Fixed in: 10.0.14393.9339
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: < 10.0.17763.9020
Fixed in: 10.0.17763.9020
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: < 10.0.20348.5386
Fixed in: 10.0.20348.5386
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.
Exact fixes by distribution
A distro patch exists: prefer upgrading over downgrading.
Fedora 46 · gcl · FIXED · 2.7.1-12.fc46 · FEDORA-2026-ff383a759b · source
sudo dnf upgrade --advisory=FEDORA-2026-ff383a759b
Fedora ELN · mozjs140 · FIXED · 140.13.0-5.eln159 · FEDORA-2026-f7ed0026e0 · source
sudo dnf upgrade --advisory=FEDORA-2026-f7ed0026e0
Windows 10 Version 1809 for 32-bit Systems · KB5099538 · FIXED · 10.0.17763.9020 · KB5099538 · source
Install KB5099538 via Windows Update, then verify:
Get-HotFix -Id KB5099538
Windows 10 Version 1809 for x64-based Systems · KB5099538 · FIXED · 10.0.17763.9020 · KB5099538 · source
Install KB5099538 via Windows Update, then verify:
Get-HotFix -Id KB5099538
Install KB5099538 via Windows Update, then verify:
Get-HotFix -Id KB5099538
Windows Server 2019 (Server Core installation) · KB5099538 · FIXED · 10.0.17763.9020 · KB5099538 · source
Install KB5099538 via Windows Update, then verify:
Get-HotFix -Id KB5099538
Install KB5099540 via Windows Update, then verify:
Get-HotFix -Id KB5099540
Verify at the official source NVD · 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.
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-2026-50518?
windows 10 1607: upgrade to 10.0.14393.9339; windows 10 1809: upgrade to 10.0.17763.9020; windows server 2012: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.
Is CVE-2026-50518 being exploited?
CVE-2026-50518 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-2026-50518 affect?
CVE-2026-50518 affects windows 10 1607, windows 10 1809, windows server 2012. Severity is critical (CVSS 9.8). Heap-based buffer overflow in Windows DHCP Server allows an unauthorized attacker to execute code over a network.
How urgent is CVE-2026-50518?
Priority 63/100. Critical severity; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action; On your watchlist
Software pages
Windows vulnerabilities · Windows Server vulnerabilities
Related CVEs
- CVE-2026-27909 HIGH 7.8 UPGRADE UPGRADE Use after free in Microsoft Windows Search Component allows an authorized attacker to elevate privileges local
- CVE-2026-32157 HIGH 8.8 UPGRADE UPGRADE Use after free in Remote Desktop Client allows an unauthorized attacker to execute code over a network.
- CVE-2026-26151 HIGH 7.1 UPGRADE UPGRADE Insufficient ui warning of dangerous operations in Windows Remote Desktop allows an unauthorized attacker to p
- CVE-2026-32077 HIGH 7.8 UPGRADE UPGRADE Untrusted pointer dereference in Windows Universal Plug and Play (UPnP) Device Host allows an authorized attac
- CVE-2026-26180 HIGH 7.8 UPGRADE UPGRADE Heap-based buffer overflow in Windows Kernel allows an authorized attacker to elevate privileges locally.