Bug 1642545 (CVE-2018-16841)

Summary:	CVE-2018-16841 samba: Double-free in Samba AD DC KDC with PKINIT
Product:	[Other] Security Response	Reporter:	Laura Pardo <lpardo>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED NOTABUG	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	abhgupta, abokovoy, anoopcs, asn, bmcclain, dbaker, dblechte, dfediuck, eedri, gdeschner, jarrpa, jokerman, jstephen, lmohanty, madam, mgoldboi, michal.skrivanek, rhs-smb, sankarshan, sbonazzo, sbose, security-response-team, sherold, sisharma, smohan, ssaha, ssorce, sthangav, trankin, vbellur
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	samba 4.7.12, samba 4.8.7, samba 4.9.3	Doc Type:	If docs needed, set a value
Doc Text:	A double-free was found when Samba's KDC is used as an Active Directory Domain Controller. An authenticated attacker could use this flaw to cause a denial of service (application crash).	Story Points:	---
Clone Of:		Environment:
Last Closed:	2018-11-28 07:16:35 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:	1654082
Bug Blocks:	1642548

Description Laura Pardo 2018-10-24 16:04:11 UTC

A flaw was found in Samba from 4.3.0 versions. When configured to accept smart-card authentication, Samba's KDC will call talloc_free() twice on the same memory if the principal in a validly signed certificate does not match the principal in the AS-REQ. This is only possible after authentication with a trusted certificate. This could result in a Denial of Service attack.

Comment 1 Sam Fowler 2018-11-28 01:55:07 UTC

External Reference:

https://www.samba.org/samba/security/CVE-2018-16841.html

Comment 2 Sam Fowler 2018-11-28 01:55:42 UTC

Created samba tracking bugs for this issue:

Affects: fedora-all [bug 1654082]

Comment 3 Sam Fowler 2018-11-28 01:56:47 UTC

Acknowledgments:

Name: The Samba Team
Upstream: Alex MacCuish

Comment 4 Huzaifa S. Sidhpurwala 2018-11-28 07:16:52 UTC

Statement:

This flaw does not affect the version of samba shipped with Red Hat Enterprise Linux because there is no support for samba as Active Directory Domain Controller.