How severe is CVE-2021-26424?

CVE-2021-26424 has a CVSS 3.x base score of 9.9, rated critical severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-26424 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 59% (99th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-26424?

CVE-2021-26424 primarily affects Microsoft Windows 10. In total, 18 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-26424?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2021-26424 published?

CVE-2021-26424 was published on 2021-08-12 and last updated on 2026-06-17.

CVE-2021-26424

CVE-2021-26424 is a critical-severity vulnerability in Microsoft Windows 10 with a CVSS 3.x base score of 9.9. Its EPSS exploit-prediction score of 59% places it in the 99th percentile, indicating an elevated likelihood of exploitation.

Key facts

Severity: Critical (CVSS 3.x base score 9.9)
CVSS v2: 6.8
EPSS exploit prediction: 59% (99th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Microsoft Windows 10
Published: 2021-08-12
Last modified: 2026-06-17

Description

Windows TCP/IP Remote Code Execution Vulnerability

Frequently asked questions

What is CVE-2021-26424?: Windows TCP/IP Remote Code Execution Vulnerability
How severe is CVE-2021-26424?: CVE-2021-26424 has a CVSS 3.x base score of 9.9, rated critical severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-26424 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 59% (99th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-26424?: CVE-2021-26424 primarily affects Microsoft Windows 10. In total, 18 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-26424?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-26424 published?: CVE-2021-26424 was published on 2021-08-12 and last updated on 2026-06-17.

References

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26424

Affected products (18)

cpe:2.3:o:microsoft:windows_10:-:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_10:20h2:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_10:21h1:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_10:1607:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_10:1809:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_10:1909:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_10:2004:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_7:-:sp1:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_8.1:-:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_rt_8.1:-:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2008:-:sp2:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2008:r2:sp1:*:*:*:*:x64:*
cpe:2.3:o:microsoft:windows_server_2012:-:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2012:r2:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2016:-:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2016:20h2:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2016:2004:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2019:-:*:*:*:*:*:*:*

More vulnerabilities in Microsoft Windows 10

CVE-2020-1467 — Critical (CVSS 10.0): An elevation of privilege vulnerability exists when Windows improperly handles hard links. An attacker who successfully…
CVE-2021-28476 — Critical (CVSS 9.9): Windows Hyper-V Remote Code Execution Vulnerability
CVE-2021-26867 — Critical (CVSS 9.9): Windows Hyper-V Remote Code Execution Vulnerability
CVE-2020-1112 — Critical (CVSS 9.9): An elevation of privilege vulnerability exists when the Windows Background Intelligent Transfer Service (BITS) IIS…
CVE-2019-1384 — Critical (CVSS 9.9): A security feature bypass vulnerability exists where a NETLOGON message is able to obtain the session key and sign…
CVE-2019-1365 — Critical (CVSS 9.9): An elevation of privilege vulnerability exists when Microsoft IIS Server fails to check the length of a buffer prior to…

All CVEs affecting Microsoft Windows 10 →