CVE-2020-17049

Kerberos KDC Security Feature Bypass Vulnerability

MEDIUM

6.6

CVSS Score

Published: November 11, 2020 at 12:00 AM UTC

Updated: June 17, 2026 at 02:58 AM UTC

9 products affected across 2 vendorsWindows Server 2016Windows Server 2019Windows Server 2012

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Severity

MEDIUM6.6

Exploit prediction

EPSS 14%

SSVC

No known exploit

Description

A security feature bypass vulnerability exists in the way Key Distribution Center (KDC) determines if a service ticket can be used for delegation via Kerberos Constrained Delegation (KCD). To exploit the vulnerability, a compromised service that is configured to use KCD could tamper with a service ticket that is not valid for delegation to force the KDC to accept it. The update addresses this vulnerability by changing how the KDC validates service tickets used with KCD.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Windows Server 2004 · Microsoft

95%

10.0.0 ≤ v < 10.0.19041.111010.0.0 10.0.19041.1110

Affected range stops below 10.0.19041.1110, so it looks safe — our inference, not a vendor statement

Windows Server 2012 · Microsoft

95%

6.2.0 ≤ v < 6.2.9200.234096.3.0 ≤ v < 6.3.9600.200696.2.0 6.2.9200.23409 6.3.0 r2

Affected range stops below 6.2.9200.23409, so it looks safe — our inference, not a vendor statement

Affected range stops below 6.3.9600.20069, so it looks safe — our inference, not a vendor statement

Windows Server 2016 · Microsoft

95%

10.0.0 ≤ v < 10.0.14393.453010.0.0 10.0.14393.4530 1903 1909 2004 20h2

Affected range stops below 10.0.14393.4530, so it looks safe — our inference, not a vendor statement

Windows Server 2019 · Microsoft

95%

10.0.0 ≤ v < 10.0.17763.206110.0.0 10.0.17763.2061

Affected range stops below 10.0.17763.2061, so it looks safe — our inference, not a vendor statement

SAMBA · Samba

95%

4.1.0 ≤ v < 4.13.134.14.0 ≤ v < 4.14.94.15.0 ≤ v < 4.15.1

Affected range stops below 4.13.13, so it looks safe — our inference, not a vendor statement

Affected range stops below 4.14.9, so it looks safe — our inference, not a vendor statement

Affected range stops below 4.15.1, so it looks safe — our inference, not a vendor statement

Windows Server 1903 · Microsoft

60%

10.0.0 ≤ v < publication10.0.0

Affected range stops below publication, so it looks safe — our inference, not a vendor statement

Windows Server 1909 · Microsoft

60%

10.0.0 ≤ v < publication10.0.0

Affected range stops below publication, so it looks safe — our inference, not a vendor statement

Windows Server 2008 · Microsoft

60%

6.0.0 ≤ v < 6.0.6003.211676.0.0 ≤ v < 6.1.7601.256616.1.0 ≤ v < 6.1.7601.256616.0.0 6.1.0

Affected range stops below 6.0.6003.21167, so it looks safe — our inference, not a vendor statement

Affected range stops below 6.1.7601.25661, so it looks safe — our inference, not a vendor statement

Windows Server 20H2 · Microsoft

60%

10.0.0 ≤ v < 10.0.19041.111010.0.0

Affected range stops below 10.0.19041.1110, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (3)

Mailing ListThird Party Advisory

Source: [email protected]

http://www.openwall.com/lists/oss-security/2021/11/10/3

PatchVendor Advisory

Source: [email protected]

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-17049

Vendor Advisory

Source: [email protected]

https://security.gentoo.org/glsa/202309-06

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.6MEDIUMmicrosoft

Vector?

Quick Info

StatusMODIFIED

CWE

CWE-863

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