CVE-2026-50509: Deserialization of untrusted data in Windows Wireless Wide Area Network Service allows an authorized attacker

Q: How do I fix CVE-2026-50509?

windows 10 1607: upgrade to 10.0.14393.9339; windows 10 1809: upgrade to 10.0.17763.9020; windows 10 21h2: upgrade to 10.0.19044.7548. Exact commands for each OS are on this page.

Q: Is CVE-2026-50509 being exploited?

CVE-2026-50509 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-50509 affect?

CVE-2026-50509 affects windows 10 1607, windows 10 1809, windows 10 21h2. Severity is high (CVSS 7.8). Deserialization of untrusted data in Windows Wireless Wide Area Network Service allows an authorized attacker to elevate privileges locally.

Q: How urgent is CVE-2026-50509?

Priority 55/100. High severity; On your watchlist

This month

HIGH 7.8WATCHLISTUPGRADEUPGRADEUPGRADE

CVE-2026-50509 is a high-severity flaw (CVSS 7.8) affecting windows 10 1607, windows 10 1809, windows 10 21h2. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Deserialization of untrusted data in Windows Wireless Wide Area Network Service allows an authorized attacker to elevate privileges locally.

Why this priority

High severity
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	7.8 (High)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	3.5% (top 11%)
CISA exploited list	No
Weakness	CWE-502
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

2026-07-14 18:17 UTCPublished CVE record published
2026-07-22 15:05 UTCUpdated 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 10 21h2 UPGRADE

Affected: < 10.0.19044.7548

Fixed in: 10.0.19044.7548

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 22h2 UPGRADE

Affected: < 10.0.19045.7548

Fixed in: 10.0.19045.7548

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 11 24h2 UPGRADE

Affected: < 10.0.26100.8875

Fixed in: 10.0.26100.8875

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 11 25h2 UPGRADE

Affected: < 10.0.26200.8875

Fixed in: 10.0.26200.8875

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

Fedora ELN · gram_grep · FIXED · 0.10.3-2.eln159 · FEDORA-2026-29427819d0 · source

sudo dnf upgrade --advisory=FEDORA-2026-29427819d0

Fedora 46 · python3.11 · FIXED · 3.11.18-1.fc46 · FEDORA-2026-cc775894f4 · source

sudo dnf upgrade --advisory=FEDORA-2026-cc775894f4

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

Windows Server 2019 · KB5099538 · FIXED · 10.0.17763.9020 · KB5099538 · source

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

Windows 10 Version 21H2 for 32-bit Systems · KB5099539 · FIXED · 10.0.19044.7548 · KB5099539 · source

Install KB5099539 via Windows Update, then verify: Get-HotFix -Id KB5099539

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.

Quick answers

How do I fix CVE-2026-50509?

windows 10 1607: upgrade to 10.0.14393.9339; windows 10 1809: upgrade to 10.0.17763.9020; windows 10 21h2: upgrade to 10.0.19044.7548. Exact commands for each OS are on this page.

Is CVE-2026-50509 being exploited?

CVE-2026-50509 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-2026-50509 affect?

CVE-2026-50509 affects windows 10 1607, windows 10 1809, windows 10 21h2. Severity is high (CVSS 7.8). Deserialization of untrusted data in Windows Wireless Wide Area Network Service allows an authorized attacker to elevate privileges locally.

How urgent is CVE-2026-50509?

Priority 55/100. High severity; On your watchlist

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References

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