How severe is CVE-2021-26896?

CVE-2021-26896 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-26896 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 7% (93rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-26896?

CVE-2021-26896 primarily affects Microsoft Windows Server 2008. In total, 10 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-26896?

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

When was CVE-2021-26896 published?

CVE-2021-26896 was published on 2021-03-11 and last updated on 2026-06-17.

CVE-2021-26896

CVE-2021-26896 is a high-severity vulnerability in Microsoft Windows Server 2008 with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 7% (93rd percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Microsoft Windows Server 2008
Published: 2021-03-11
Last modified: 2026-06-17

Description

Windows DNS Server Denial of Service Vulnerability

Frequently asked questions

What is CVE-2021-26896?: Windows DNS Server Denial of Service Vulnerability
How severe is CVE-2021-26896?: CVE-2021-26896 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-26896 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 7% (93rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-26896?: CVE-2021-26896 primarily affects Microsoft Windows Server 2008. In total, 10 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-26896?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-26896 published?: CVE-2021-26896 was published on 2021-03-11 and last updated on 2026-06-17.

References

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26896

Affected products (10)

cpe:2.3:o:microsoft:windows_server_2008:r2:sp1:*:*:*:*:x64:*
cpe:2.3:o:microsoft:windows_server_2008:sp2:*:*:*:*:*:x64:*
cpe:2.3:o:microsoft:windows_server_2008:sp2:*:*:*:*:*:x86:*
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_2016:1909:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2016:2004:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2019:-:*:*:*:*:*:*:*

More vulnerabilities in Microsoft Windows Server 2008

CVE-2020-1467 — Critical (CVSS 10.0): An elevation of privilege vulnerability exists when Windows improperly handles hard links. An attacker who successfully…
CVE-2020-1350 — Critical (CVSS 10.0): A remote code execution vulnerability exists in Windows Domain Name System servers when they fail to properly handle…
CVE-2015-0014 — Critical (CVSS 10.0): Buffer overflow in the Telnet service in Microsoft Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2…
CVE-2014-6321 — Critical (CVSS 10.0): Schannel in Microsoft Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1,…
CVE-2013-3195 — Critical (CVSS 10.0): The DSA_InsertItem function in Comctl32.dll in the Windows common control library in Microsoft Windows XP SP2, Windows…
CVE-2013-3175 — Critical (CVSS 10.0): Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1,…

All CVEs affecting Microsoft Windows Server 2008 →