CVE-2018-20217

Name: CVE-2018-20217
Creator: NVD / NIST
Published: 2018-12-26T21:29:02.543+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.3/10EPSS 1.53%

Last modified Jun 17, 2026

CVE-2018-20217 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. A Reachable Assertion issue was discovered in the KDC in MIT Kerberos 5 (aka krb5) before 1.17. If an attacker can obtain a krbtgt ticket using an older encryption type (single-DES, triple-DES, or RC4), the attacker can crash the KDC by making an S4U2Self request.. EPSS estimates a 1.53% chance of exploitation in the next 30 days.

Description

A Reachable Assertion issue was discovered in the KDC in MIT Kerberos 5 (aka krb5) before 1.17. If an attacker can obtain a krbtgt ticket using an older encryption type (single-DES, triple-DES, or RC4), the attacker can crash the KDC by making an S4U2Self request.

Metrics

CVSS 3.1

5.3/10

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

EPSS Probability

1.53%

71.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-617

Affected Software

Vendor	Product	Versions
Mit	Kerberos	< 5-1.17
Debian	Debian Linux	8.0
Debian	Debian Linux	9.0

References

http://krbdev.mit.edu/rt/Ticket/Display.html?id=8763Patch, Third Party Advisory
https://github.com/krb5/krb5/commit/5e6d1796106df8ba6bc1973ee0917c170d929086Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2019/01/msg00020.htmlMailing List, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/09/msg00019.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2KNHELH4YHNT6H2ESJWX2UIDXLBNGB2O/
https://security.netapp.com/advisory/ntap-20190416-0006/Third Party Advisory
http://krbdev.mit.edu/rt/Ticket/Display.html?id=8763Patch, Third Party Advisory
https://github.com/krb5/krb5/commit/5e6d1796106df8ba6bc1973ee0917c170d929086Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2019/01/msg00020.htmlMailing List, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/09/msg00019.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2KNHELH4YHNT6H2ESJWX2UIDXLBNGB2O/
https://security.netapp.com/advisory/ntap-20190416-0006/Third Party Advisory

Timeline

Published: Dec 26, 2018
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2018-20217?

How severe is CVE-2018-20217?

CVE-2018-20217 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 1.53% probability of exploitation in the next 30 days.

How do I fix CVE-2018-20217?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2018-20217?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST