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: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED NOTABUG QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: abhgupta, abokovoy, anoopcs, asn, bmcclain, dbaker, dblechte, dfediuck, eedri, gdeschner, jokerman, jrivera, 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: impact=moderate,public=20181128,reported=20181024,source=upstream,cvss3=5.7/CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H,cwe=CWE-416,rhes-3/samba=notaffected,rhel-7/samba=notaffected,rhel-8/samba=notaffected,rhev-m-4/samba=notaffected,rhel-6/samba4=notaffected,fedora-all/samba=affected,openshift-online-3/samba=notaffected
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: ---
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.