CVE-2020-17049
Kerberos KDC Security Feature Bypass Vulnerability
- Published
- Updated
- Reserved
- Assigned by
- microsoft
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.
Timeline
ID reserved
By microsoft
- 3 months later
· 3 months later
Published
- 4 years later
· 4 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| microsoftCNA (assigner) | 3.1 | Medium6.6 | CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C |
| NVDNVD · Modified | 3.1 | Medium6.6 | CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 13.8% · top 3.5% of all CVEs (7 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.6.
Weakness
- Security Feature Bypass
- CWE-863 (opens in a new tab)All about CWE-863 and its CVEs
Affected products
Microsoft · Windows Server 2019
- affected 10.0.0 – < 10.0.17763.2061
Microsoft · Windows Server 2019 (Server Core installation)
- affected 10.0.0 – < 10.0.17763.2061
Microsoft · Windows Server, version 1909 (Server Core installation)
- affected 10.0.0 – < publication
Microsoft · Windows Server, version 1903 (Server Core installation)
- affected 10.0.0 – < publication
Microsoft · Windows Server version 2004
- affected 10.0.0 – < 10.0.19041.1110
Microsoft · Windows Server 2016
- affected 10.0.0 – < 10.0.14393.4530
Microsoft · Windows Server 2016 (Server Core installation)
- affected 10.0.0 – < 10.0.14393.4530
Microsoft · Windows Server 2008 Service Pack 2
- affected 6.0.0 – < 6.0.6003.21167
Microsoft · Windows Server 2008 Service Pack 2 (Server Core installation)
- affected 6.0.0 – < 6.0.6003.21167
Microsoft · Windows Server 2008 Service Pack 2
- affected 6.0.0 – < 6.0.6003.21167
Microsoft · Windows Server 2008 R2 Service Pack 1
- affected 6.1.0 – < 6.1.7601.25661
Microsoft · Windows Server 2008 R2 Service Pack 1 (Server Core installation)
- affected 6.0.0 – < 6.1.7601.25661
Microsoft · Windows Server 2012
- affected 6.2.0 – < 6.2.9200.23409
Microsoft · Windows Server 2012 (Server Core installation)
- affected 6.2.0 – < 6.2.9200.23409
Microsoft · Windows Server 2012 R2
- affected 6.3.0 – < 6.3.9600.20069
Microsoft · Windows Server 2012 R2 (Server Core installation)
- affected 6.3.0 – < 6.3.9600.20069
Microsoft · Windows Server version 20H2
- affected 10.0.0 – < 10.0.19041.1110
References (3)
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-17049 (opens in a new tab)x_transferred
- [oss-security] 20211110 Fwd: Samba 4.15.2, 4.14.10, 4.13.14 Security Releases are available for Download (opens in a new tab)mailing-listx_transferred
- GLSA-202309-06 (opens in a new tab)vendor-advisoryx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2020-17049)Record last updated .