Bug 1438676 (CVE-2017-2669)

Summary:	CVE-2017-2669 dovecot: Dovecot DoS when passdb dict was used for authentication
Product:	[Other] Security Response	Reporter:	Adam Mariš <amaris>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED NOTABUG	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	dexter, janfrode, mhlavink, pokorra.mailinglists, security-response-team
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	dovecot 2.2.29	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2017-04-11 05:44:56 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:	1441457
Bug Blocks:	1438677

Description Adam Mariš 2017-04-04 07:50:15 UTC

When "dict" passdb and userdb were used for user authentication, the username sent by the IMAP/POP3 client was sent through var_expand() to perform %variable expansion. Sending specially crafted %variable fields could result in excessive memory usage causing the process to crash (and restart), or excessive CPU usage causing all authentications to hang.

This issue was introduced by:

https://github.com/dovecot/core/commit/a3783f8a3c9cd816b51e77a922f82301512fcf22

Upstream patch:

https://github.com/dovecot/core/commit/000030feb7a30f193197f1aab8a7b04a26b42735.patch

Vulnerable versions: 2.2.26 - 2.2.28

Comment 1 Adam Mariš 2017-04-04 07:50:22 UTC

Acknowledgments:

Name: the Dovecot project

Comment 5 Doran Moppert 2017-04-12 01:58:46 UTC

According to analysis conducted by Red Hat and Debian, and acknowledged by the Dovecot project, versions prior to 2.2.26 were not affected by this issue.

Comment 6 Doran Moppert 2017-04-12 01:58:58 UTC

Statement:

Versions of dovecot shipped in Red Hat Enterprise Linux 5, 6 and 7 are not affected by this vulnerability.

Comment 7 Doran Moppert 2017-04-12 01:59:28 UTC

Created dovecot tracking bugs for this issue:

Affects: fedora-all [bug 1441457]