Bug 1665296 (CVE-2018-20217)

Summary:	CVE-2018-20217 krb5: Reachable assertion in the KDC using S4U2Self requests
Product:	[Other] Security Response	Reporter:	Laura Pardo <lpardo>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	apmukher, cheimes, dpal, jplans, lpardo, nalin, pkis, rlinga, rschiron
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	krb5 1.17	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-10-27 03:19:05 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1665297, 1673016, 1673017, 1732339
Bug Blocks:	1665299

Description Laura Pardo 2019-01-10 21:45:52 UTC

A vulnerability was found in in the KDC in MIT Kerberos 5 (aka krb5) before 1.17. An authenticated user who can obtain a TGT using an older encryption type (DES, DES3, or RC4) can cause an assertion failure in the KDC by sending an S4U2Self request.


References:
http://krbdev.mit.edu/rt/Ticket/Display.html?id=8763
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/2KNHELH4YHNT6H2ESJWX2UIDXLBNGB2O/

Upstream Patch:
https://github.com/krb5/krb5/commit/94e5eda5bb94d1d44733a49c3d9b6d1e42c74def

Comment 1 Laura Pardo 2019-01-10 21:46:24 UTC

Created krb5 tracking bugs for this issue:

Affects: fedora-all [bug 1665297]

Comment 7 Rama 2019-02-20 22:45:39 UTC

Why is it that Status is New and Fixed In says 1.17? Is this bug really fixed in RHEL 7?
If so, is there a CentOS 7.x RPM with this fix already?

Comment 8 Robbie Harwood 2019-02-21 17:04:38 UTC

Hi Rama, 1.17 is the krb5 version that it's fixed in upstream.

This is the RHEL/Fedora bugtracker; CentOS bugs are tracked separately (by different people) at https://bugs.centos.org

Comment 10 Rama 2019-03-01 06:19:48 UTC

Hi Robbie,

We currently bundle krb5-libs-1.15.1-19.el7.x86_64 and krb5-devel-1.15.1-19.el7.x86_64 on the top of the CentOS 7.5.1804. 
And we are trying to fix cve-2018-20217. Idea is to apply the upstream patch onto this source and rebuild source RPM and RPM for 1.17.

I will be raising this question on CentOS forum as suggested.
Would appreciate if you can share your thoughts as you are involved with krb5 development.

Comment 12 Joshua Padman 2019-05-15 22:55:17 UTC

This vulnerability is out of security support scope for the following product:
 * Red Hat Enterprise Application Platform 6

Please refer to https://access.redhat.com/support/policy/updates/jboss_notes for more details.

Comment 13 Joshua Padman 2019-07-10 05:32:51 UTC

This vulnerability is out of security support scope for the following product:
 * Red Hat JBoss Core Services
 * Red Hat JBoss Enterprise Web Server 2

Please refer to https://access.redhat.com/support/policy/updates/jboss_notes for more details.