CVE-2021-26424
CriticalWindows TCP/IP Remote Code Execution Vulnerability
Published Aug 12, 2021 · Updated Aug 10, 2026
Key Facts
Patch immediately- CVE-2021-26424 is a critical-severity vulnerability (CVSS 9.8 v3.1) affecting Windows 10 (Microsoft), Windows 10 1507 (Microsoft), Windows 10 1607 (Microsoft) and 16 more products.
- It is not listed in any known-exploited vulnerabilities catalog. No public exploit code is known.
- EPSS estimates a 61% probability of exploitation in the next 30 days.
- Fixed versions are available, including Windows 10 1507 10.0.10240.19022, Windows 10 1607 10.0.14393.4583, Windows 10 1809 10.0.17763.2114.
- Brandefense priority: patch immediately, because it is very likely to be exploited soon.
CVSS v3.1
9.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
61%
Higher than 99.1% of all scored CVEs
Exploited in the wild
No known
Not in a known-exploited catalog
Public exploit code
None known
Get the full CVE-2021-26424 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
Description
Windows TCP/IP Remote Code Execution Vulnerability
Affected Products
48 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Windows 10Microsoft | 1607, 1809, 1909, 2004, 20h2, 21h1 | n/a |
| Windows 10 1507Microsoft | 10.0.10240.19022 | 10.0.10240.19022 |
| Windows 10 1607Microsoft | 10.0.14393.4583 | 10.0.14393.4583 |
| Windows 10 1809Microsoft | 10.0.17763.2114, 10.0.18363.1734, 10.0.19041.1165 | 10.0.17763.2114 |
| Windows 10 1909Microsoft | 10.0.18363.1734 | 10.0.18363.1734 |
Patched Releases
Windows 10 1507
10.0.10240.19022
Windows 10 1607
10.0.14393.4583
Windows 10 1809
10.0.17763.2114, 10.0.18363.1734, 10.0.19041.1165
Windows 10 1909
10.0.18363.1734
windows 10 20H2
10.0.19042.1165
windows 10 21H1
10.0.19043.1165
Windows 7
6.1.7601.25685
Windows 8.1
6.3.9600.20094
Windows Rt 8.1
6.3.9600.20094
Windows Server 2004
10.0.19041.1165
windows server 2008 R2
6.1.7601.25685
Windows Server 2008 Sp2
6.0.6003.21192
Windows Server 2012
6.2.9200.23435
windows server 2012 R2
6.3.9600.20094
Windows Server 2016
10.0.14393.4583
Windows Server 2019
10.0.17763.2114
windows server 20H2
10.0.19042.1165
Timeline
Publicly disclosed
Aug 12, 2021
Last updated
Aug 10, 2026
References
FAQ
Common Questions.
Windows TCP/IP Remote Code Execution Vulnerability
Affected: Windows 10 (Microsoft) versions 1607, 1809, 1909, 2004, 20h2, 21h1; Windows 10 1507 (Microsoft) versions 10.0.10240.19022; Windows 10 1607 (Microsoft) versions 10.0.14393.4583, among others. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
No public exploit code is known.
Fixed versions are available, including Windows 10 1507 10.0.10240.19022, Windows 10 1607 10.0.14393.4583, Windows 10 1809 10.0.17763.2114.
Brandefense priority: patch immediately, because it is very likely to be exploited soon.
Is CVE-2021-26424 Running On Your Attack Surface?
Brandefense maps vulnerabilities like this one to your internet-facing assets and tells you exactly where to patch.
Request A Demo