Summary
Impact: Elevation of Privilege. Microsoft rating: Important. Not known to be exploited — Exploitation Unlikely. Customer action: Required.
Details
According to the CVSS metric, the attack complexity is high (AC:H). What does that mean for this vulnerability?
A high attack complexity means the attacker must be able to perform a precise machine‑in‑the‑middle modification of Kerberos traffic, which requires specific network positioning and conditions to succeed.
What privileges could be gained by an attacker who successfully exploited this vulnerability?
An attacker who successfully exploited this vulnerability could gain SYSTEM privileges.
Security updates
10.0.17763.8276 — https://support.microsoft.com/help/5073723
10.0.20348.4648 — https://support.microsoft.com/help/5073457
10.0.19044.6809 — https://support.microsoft.com/help/5073724
10.0.26100.32230 — https://support.microsoft.com/en-us/topic/a6021fd2-b3b7-45a7-b68e-35c28a2a77da
10.0.26200.7623 — https://support.microsoft.com/help/5074109
10.0.22631.6491 — https://support.microsoft.com/help/5073455
10.0.25398.2092 — https://support.microsoft.com/help/5073450
10.0.14393.8783 — https://support.microsoft.com/help/5073722
6.0.6003.23717 — https://support.microsoft.com/help/5073697
6.0.6003.23717 — https://support.microsoft.com/help/5073700
6.1.7601.28117 — https://support.microsoft.com/help/5073695
6.1.7601.28117 — https://support.microsoft.com/help/5073699
6.2.9200.25868 — https://support.microsoft.com/help/5073698
6.3.9600.22968 — https://support.microsoft.com/help/5073696
Vulnerabilities 1
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High 7.5
Windows Kerberos Elevation of Privilege Vulnerability
Reliance on untrusted inputs in a security decision in Windows Kerberos allows an authorized attacker to elevate privileges over a network.
Revision history
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#1
Information published.
References
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CVE-2026-20849 Windows Kerberos Elevation of Privilege Vulnerability - HTML
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20849
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Microsoft Exploitability Index
https://www.microsoft.com/en-us/msrc/exploitability-index?rtc=1
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Microsoft Support Lifecycle
https://support.microsoft.com/lifecycle
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Common Vulnerability Scoring System
https://www.first.org/cvss