Is CVE-2021-26866 in the CISA KEV catalog?

No. CVE-2021-26866 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-26866?

CVE-2021-26866 has a CVSS v3 base score of 7.1 (HIGH).

What is the EPSS score for CVE-2021-26866?

CVE-2021-26866 has an EPSS score of 1.11% (62th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-26866?

Install KB5000807 for Windows 10. Fixes are available for 14 affected products.

CVE & CISA-KEV Catalog

CVE-2021-26866

HIGH

7.1

CVSS v3

NVD

Description

Windows Update Service Elevation of Privilege Vulnerability

CWE-59Link Following

How to fix

Remediation Available

Windows 10Windows

Install:KB5000807Microsoft

Windows 10 Version 1607Windows

Install:KB5000803Microsoft

Windows 10 Version 1803Windows

Install:KB5000809Microsoft

Windows 10 Version 1809Windows

Install:KB5000822Microsoft

Windows 10 Version 1909Windows

Install:KB5000808Microsoft

Windows 10 Version 2004Windows

Install:KB5000802Microsoft

Windows 10 Version 20H2Windows

Install:KB5000802Microsoft

Windows Server 2016Windows

Install:KB5000803Microsoft

Windows Server 2016 (Server Core installation)Windows

Install:KB5000803Microsoft

Windows Server 2019Windows

Install:KB5000822Microsoft

Windows Server 2019 (Server Core installation)Windows

Install:KB5000822Microsoft

Windows Server, version 1909 (Server Core installation)Windows

Install:KB5000808Microsoft

Windows Server, version 2004 (Server Core installation)Windows

Install:KB5000802Microsoft

Windows Server, version 20H2 (Server Core Installation)Windows

Install:KB5000802Microsoft

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorLocal

Attack ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

Exploit Intelligence

1.11%probability of exploitation in 30 days

62ndpercentile

Moderate risk: more likely to be exploited than 62% of all known CVEs.

References

Patch1

portal.msrc.microsoft.com

Third-Party Advisory1

zerodayinitiative.com

Related Vulnerabilities

Other CWE-59 (Link Following) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2022-30333	High	7.5	99%	KEV + Ransom	Fix
CVE-2021-21300	High	8.0	89%	-	Fix
CVE-2021-32610	High	7.1	73%	-	Fix
CVE-2020-36193	High	7.5	71%	KEV	Fix
CVE-2023-40028	Medium	4.9	58%	-	Fix
CVE-2020-0787	High	7.8	43%	KEV + Ransom	-

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2024-11-21.