Bug 1866313 (CVE-2020-12673)

Summary: CVE-2020-12673 dovecot: Out of bound reads in dovecot NTLM implementation
Product: [Other] Security Response Reporter: Huzaifa S. Sidhpurwala <huzaifas>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED ERRATA QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: anon.amish, bennie.joubert, janfrode, mhlavink, security-response-team
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: dovecot 2.3.11 Doc Type: If docs needed, set a value
Doc Text:
A flaw was found in dovecot. An out-of-bounds read flaw was found in the way dovecot handled NTLM authentication allowing an attacker to crash the dovecot auth process repeatedly preventing login. The highest threat from this vulnerability is to system availability.
 Story Points: ---
Clone Of: Environment:
Last Closed: 2020-09-03 13:17:46 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: 1866757, 1866758, 1866759, 1866760, 1866761, 1868540, 1871843    
Bug Blocks: 1866310    
Attachments:
Description Flags
Upstream patch none

Description Huzaifa S. Sidhpurwala 2020-08-05 10:55:27 UTC 
As per upstream:

Vulnerability Details:
Dovecot's NTLM implementation does not correctly check message buffer size, which leads to reading past allocation which can lead to crash.

Risk:
An adversary can use this vulnerability to crash dovecot auth process repeatedly, preventing login.
Comment 2 Huzaifa S. Sidhpurwala 2020-08-06 03:57:39 UTC 
Created attachment 1710594 [details]
Upstream patch
Comment 6 Huzaifa S. Sidhpurwala 2020-08-06 09:30:19 UTC 
Mitigation:

Upstream suggests that this flaw can be mitigated by disabling NTLM authentication. NTLM authentication can be disabled by using the configuration parameter "auth_mechanisms". More details available at: https://doc.dovecot.org/configuration_manual/authentication/authentication_mechanisms/
Comment 7 Huzaifa S. Sidhpurwala 2020-08-06 09:32:55 UTC 
Acknowledgments:

Name: the Dovecot project
Comment 8 Huzaifa S. Sidhpurwala 2020-08-13 03:52:46 UTC 
External References:

https://dovecot.org/pipermail/dovecot-news/2020-August/000442.html
Comment 9 Huzaifa S. Sidhpurwala 2020-08-13 03:53:21 UTC 
Created dovecot tracking bugs for this issue:

Affects: fedora-all [bug 1868540]
Comment 10 Huzaifa S. Sidhpurwala 2020-08-13 04:05:07 UTC 
Upstream patch: https://github.com/dovecot/core/commit/fb246611e62ad8c5a95b0ca180a63f17aa34b0d8
Comment 14 errata-xmlrpc 2020-09-03 10:34:36 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2020:3617 https://access.redhat.com/errata/RHSA-2020:3617
Comment 15 Product Security DevOps Team 2020-09-03 13:17:46 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-2020-12673
Comment 20 errata-xmlrpc 2020-09-10 12:59:59 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2020:3713 https://access.redhat.com/errata/RHSA-2020:3713
Comment 23 errata-xmlrpc 2020-09-14 12:42:39 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.0 Update Services for SAP Solutions

Via RHSA-2020:3735 https://access.redhat.com/errata/RHSA-2020:3735
Comment 24 errata-xmlrpc 2020-09-14 12:46:04 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.1 Extended Update Support

Via RHSA-2020:3736 https://access.redhat.com/errata/RHSA-2020:3736