Bug 1996834 (CVE-2021-37750)

Summary:	CVE-2021-37750 krb5: NULL pointer dereference in process_tgs_req() in kdc/do_tgs_req.c via a FAST inner body that lacks server field
Product:	[Other] Security Response	Reporter:	Guilherme de Almeida Suckevicz <gsuckevi>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	abokovoy, asoldano, atangrin, bbaranow, bdettelb, bmaxwell, brian.stansberry, cdewolf, chazlett, csutherl, darran.lofthouse, dkreling, dosoudil, dpal, eleandro, fdvorak, fjuma, gzaronik, iweiss, jclere, jochrist, jpallich, jperkins, jplans, j, jwon, krathod, kwills, lgao, msochure, msvehla, mturk, nalin, npmccallum, nwallace, pjindal, pmackay, rguimara, rstancel, rsvoboda, sbose, smaestri, ssorce, szappis, tomckay, tom.jenkinson, yborgess
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	krb5 1.18.5, krb5 1.19.3	Doc Type:	If docs needed, set a value
Doc Text:	A flaw was found in krb5. The Key Distribution Center (KDC) in MIT Kerberos 5 has a NULL pointer dereference via a FAST inner body that lacks a server field. An authenticated attacker could use this flaw to crash the Kerberos KDC server. The highest threat from this vulnerability is to system availability.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-09-21 12:28:07 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:	1996835, 1997599, 1997600, 1997601, 1997602
Bug Blocks:	1996836

Description Guilherme de Almeida Suckevicz 2021-08-23 18:59:25 UTC

The Key Distribution Center (KDC) in MIT Kerberos 5 (aka krb5) before 1.18.5 and 1.19.x before 1.19.3 has a NULL pointer dereference in kdc/do_tgs_req.c via a FAST inner body that lacks a server field.

The attacker needs to be successfully authenticated in order to carry on the attack.

Reference and upstream patch:
https://github.com/krb5/krb5/commit/d775c95af7606a51bf79547a94fa52ddd1cb7f49

Comment 1 Guilherme de Almeida Suckevicz 2021-08-23 18:59:48 UTC

Created krb5 tracking bugs for this issue:

Affects: fedora-all [bug 1996835]

Comment 4 errata-xmlrpc 2021-09-21 08:39:15 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2021:3576 https://access.redhat.com/errata/RHSA-2021:3576

Comment 5 Product Security DevOps Team 2021-09-21 12:28:07 UTC

This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

https://access.redhat.com/security/cve/cve-2021-37750

Comment 6 errata-xmlrpc 2021-11-23 17:16:02 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2021:4788 https://access.redhat.com/errata/RHSA-2021:4788