CVE-2020-17049: Kerberos KDC Security Feature Bypass Vulnerability
Noroxi assessment
Priority: Monitor (action score 30/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 13.7% (FIRST EPSS); higher than 96.5% of all records.
- Anyone who can reach it over the internet can trigger it. Administrator privileges are required. No user action is required. Special conditions such as timing or configuration are required.
- Fixed version: bind-dyndb-ldap (AlmaLinux:8) 11.6-4.module_el8.6.0+3339+9b5fdd22; custodia (AlmaLinux:8) 0.6.0-3.module_el8.6.0+2881+2f24dc92; ipa-client (AlmaLinux:8) 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1.
- Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).
Low priority for now. Upgrade to bind-dyndb-ldap (AlmaLinux:8) 11.6-4.module_el8.6.0+3339+9b5fdd22; custodia (AlmaLinux:8) 0.6.0-3.module_el8.6.0+2881+2f24dc92; ipa-client (AlmaLinux:8) 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
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.
- Published
- Nov 11, 2020
- Updated
- Jun 16, 2026
- EPSS
- 13.7% · 96th percentile
- CWE
- CWE-863
Report tools
Action score
30
Monitor
Low priority for now.
- CVSS
- 26 / 40 · 6.6 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 4 / 30 · 13.7%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · microsoft
- 6.6
- NVD has not scored this yet; the score shown is the CNA’s.
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
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
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Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| microsoft | windows server 2012 | cpe:2.3:o:microsoft:windows_server_2012 |
| microsoft | windows server 2016 | cpe:2.3:o:microsoft:windows_server_2016 |
| microsoft | windows server 2019 | cpe:2.3:o:microsoft:windows_server_2019 |
| samba | samba | cpe:2.3:a:samba:samba |
Using windows server 2012? Add it to your stack and be the first to know about CVEs like this one. (Windows Server, Active Directory)
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- microsoft windows server 2012all versions
- microsoft windows server 2012r2
- microsoft windows server 2016all versions
- microsoft windows server 20161903
- microsoft windows server 20161909
- microsoft windows server 20162004
- microsoft windows server 201620h2
- microsoft windows server 2019all versions
Versions reported by the vendor
Affected version ranges reported by the assigning authority (microsoft). Independent of NVD's CPE analysis and usually ahead of it.
Microsoft Windows Server 2008 Service Pack 2
- 6.0.0 and later · before 6.0.6003.21167affected
Microsoft Windows Server 2008 R2 Service Pack 1
- 6.1.0 and later · before 6.1.7601.25661affected
Microsoft Windows Server 2008 R2 Service Pack 1 (Server Core installation)
- 6.0.0 and later · before 6.1.7601.25661affected
Microsoft Windows Server 2008 Service Pack 2
- 6.0.0 and later · before 6.0.6003.21167affected
Microsoft Windows Server 2008 Service Pack 2 (Server Core installation)
- 6.0.0 and later · before 6.0.6003.21167affected
Microsoft Windows Server 2012
- 6.2.0 and later · before 6.2.9200.23409affected
Microsoft Windows Server 2012 (Server Core installation)
- 6.2.0 and later · before 6.2.9200.23409affected
Microsoft Windows Server 2012 R2
- 6.3.0 and later · before 6.3.9600.20069affected
Microsoft Windows Server 2012 R2 (Server Core installation)
- 6.3.0 and later · before 6.3.9600.20069affected
Microsoft Windows Server 2016
- 10.0.0 and later · before 10.0.14393.4530affected
Microsoft Windows Server 2016 (Server Core installation)
- 10.0.0 and later · before 10.0.14393.4530affected
Microsoft Windows Server 2019
- 10.0.0 and later · before 10.0.17763.2061affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| AlmaLinux:8 | bind-dyndb-ldap | before 11.6-4.module_el8.6.0+3339+9b5fdd22 | 11.6-4.module_el8.6.0+3339+9b5fdd22 |
| AlmaLinux:8 | custodia | before 0.6.0-3.module_el8.6.0+2881+2f24dc92 | 0.6.0-3.module_el8.6.0+2881+2f24dc92 |
| AlmaLinux:8 | ipa-client | before 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 | 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 |
| AlmaLinux:8 | ipa-client-common | before 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 | 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 |
| AlmaLinux:8 | ipa-client-epn | before 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 | 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 |
| AlmaLinux:8 | ipa-client-samba | before 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 | 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 |
| AlmaLinux:8 | ipa-common | before 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 | 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 |
| AlmaLinux:8 | ipa-healthcheck | before 0.12-3.module_el8.9.0+3651+d05ea4c5 | 0.12-3.module_el8.9.0+3651+d05ea4c5 |
| AlmaLinux:8 | ipa-healthcheck-core | before 0.12-3.module_el8.9.0+3651+d05ea4c5 | 0.12-3.module_el8.9.0+3651+d05ea4c5 |
| AlmaLinux:8 | ipa-python-compat | before 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 | 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 |
| AlmaLinux:8 | ipa-selinux | before 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 | 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 |
| AlmaLinux:8 | ipa-server | before 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 | 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 |
| AlmaLinux:8 | ipa-server-common | before 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 | 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 |
| AlmaLinux:8 | ipa-server-dns | before 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 | 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 |
| AlmaLinux:8 | ipa-server-trust-ad | before 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 | 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 |
| AlmaLinux:8 | opendnssec | before 2.1.7-1.module_el8.6.0+2881+2f24dc92 | 2.1.7-1.module_el8.6.0+2881+2f24dc92 |
| AlmaLinux:8 | opendnssec | before 2.1.7-1.module_el8.6.0+3031+2f24dc92 | 2.1.7-1.module_el8.6.0+3031+2f24dc92 |
| AlmaLinux:8 | python3-custodia | before 0.6.0-3.module_el8.6.0+2881+2f24dc92 | 0.6.0-3.module_el8.6.0+2881+2f24dc92 |
| AlmaLinux:8 | python3-ipaclient | before 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 | 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 |
| AlmaLinux:8 | python3-ipalib | before 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 | 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 |
| AlmaLinux:8 | python3-ipaserver | before 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 | 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 |
| AlmaLinux:8 | python3-ipatests | before 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 | 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 |
| AlmaLinux:8 | python3-jwcrypto | before 0.5.0-1.1.module_el8.7.0+3349+cfeff52e | 0.5.0-1.1.module_el8.7.0+3349+cfeff52e |
| AlmaLinux:8 | python3-kdcproxy | before 0.4-5.module_el8.9.0+3682+f63caf3e | 0.4-5.module_el8.9.0+3682+f63caf3e |
+96
Same product
microsoft: all recordsOther highest-scoring records for the same primary product.
- CVE-2025-59287Windows Server Update Service (WSUS) Remote Code Execution VulnerabilityKEV99Now
- CVE-2023-24941Windows Network File System Remote Code Execution Vulnerability67This week
- CVE-2026-41089Windows Netlogon Remote Code Execution Vulnerability63This week
Published before and after this one in the same product
- ← EarlierCVE-2020-1466Aug 17, 2020 · Windows Remote Desktop Gateway (RD Gateway) Denial of Service Vulnerability32Monitor
- ← EarlierCVE-2020-16980Oct 16, 2020 · Windows iSCSI Target Service Elevation of Privilege Vulnerability31Monitor
- Later →CVE-2020-16996Dec 9, 2020 · Kerberos Security Feature Bypass Vulnerability27Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| almalinux:bind-dyndb-ldap | 11.6-4.module_el8.6.0+3339+9b5fdd22 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:custodia | 0.6.0-3.module_el8.6.0+2881+2f24dc92 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:ipa-client | 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:ipa-client-common | 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:ipa-client-epn | 4.9.12-11.module_el8.9.0+3715+e4197dc9.alma.1 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:krb5-devel | 1.20.1-8.el9 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:krb5-libs | 1.20.1-8.el9 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:krb5-pkinit | 1.20.1-8.el9 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:krb5-server | 1.20.1-8.el9 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:krb5-server-ldap | 1.20.1-8.el9 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:krb5-workstation | 1.20.1-8.el9 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:libkadm5 | 1.20.1-8.el9 · AlmaLinux:9 | Package registry (OSV) |
| opensuse:python-impacket | 0.13.1-1.2 · openSUSE:Tumbleweed | Package registry (OSV) |
| opensuse:samba | 4.15.2+git.193.a4d6307f1fd-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| red hat:krb5 | 0:1.20.1-8.el9 · Red Hat:enterprise_linux:9::baseos | Package registry (OSV) |
| red hat:krb5-debuginfo | 0:1.20.1-8.el9 · Red Hat:enterprise_linux:9::baseos | Package registry (OSV) |
| red hat:krb5-debugsource | 0:1.20.1-8.el9 · Red Hat:enterprise_linux:9::baseos | Package registry (OSV) |
| red hat:krb5-devel | 0:1.20.1-8.el9 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:krb5-libs | 0:1.20.1-8.el9 · Red Hat:enterprise_linux:9::baseos | Package registry (OSV) |
| red hat:krb5-libs-debuginfo | 0:1.20.1-8.el9 · Red Hat:enterprise_linux:9::baseos | Package registry (OSV) |
| red hat:krb5-pkinit | 0:1.20.1-8.el9 · Red Hat:enterprise_linux:9::baseos | Package registry (OSV) |
| red hat:krb5-pkinit-debuginfo | 0:1.20.1-8.el9 · Red Hat:enterprise_linux:9::baseos | Package registry (OSV) |
| red hat:krb5-server | 0:1.20.1-8.el9 · Red Hat:enterprise_linux:9::baseos | Package registry (OSV) |
| red hat:krb5-server-debuginfo | 0:1.20.1-8.el9 · Red Hat:enterprise_linux:9::baseos | Package registry (OSV) |
| red hat:krb5-server-ldap | 0:1.20.1-8.el9 · Red Hat:enterprise_linux:9::baseos | Package registry (OSV) |
| red hat:krb5-server-ldap-debuginfo | 0:1.20.1-8.el9 · Red Hat:enterprise_linux:9::baseos | Package registry (OSV) |
| rocky linux:custodia | 0:0.6.0-3.module+el8.9.0+1371+ffa84eb9 · Rocky Linux:8 | Package registry (OSV) |
| rocky linux:ipa-healthcheck | 0:0.12-3.module+el8.9.0+1433+5bd2f890 · Rocky Linux:8 | Package registry (OSV) |
| rocky linux:opendnssec | 0:2.1.7-1.module+el8.9.0+1371+ffa84eb9 · Rocky Linux:8 | Package registry (OSV) |
| rocky linux:python-kdcproxy | 0:0.4-5.module+el8.9.0+1371+ffa84eb9 · Rocky Linux:8 | Package registry (OSV) |
+7
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
No history yet (it accumulates with the daily EPSS job).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
National notice (Türkiye Cybersecurity Directorate / USOM)
Official security notices citing this record; remediation advice is on the agency's page.
- TR-20-928 · Nov 11, 2020(Microsoft Kasım 2020 Güvenlik Güncellemelerini Yayınladı)
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- Administrator privileges are required.
- No user action is required.
- Special conditions such as timing or configuration are required.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- High
- Privileges required
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-863 · Incorrect AuthorizationCVSS vector
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (2 more)Show less
Vendor advisories and official records. Exploit/PoC links are deliberately left out.