Bug 1438676 – CVE-2017-2669 dovecot: Dovecot DoS when passdb dict was used for authentication

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Bug 1438676 - (CVE-2017-2669) CVE-2017-2669 dovecot: Dovecot DoS when passdb dict was used for authentication

Summary:	CVE-2017-2669 dovecot: Dovecot DoS when passdb dict was used for authentication

Status:	CLOSED NOTABUG

Aliases:	CVE-2017-2669

Product:	Security Response
Classification:	Other
Component:	vulnerability (Show other bugs)
Sub Component:
Version:	unspecified
Hardware:	All Linux

Priority	low Severity low
Target Milestone:	---
Target Release:	---
Assigned To:	Red Hat Product Security
QA Contact:
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URL:
Whiteboard:	impact=low,public=20170410,reported=2...
Keywords:	Security

Depends On:	1441457
Blocks:	1438677
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Reported:	2017-04-04 03:50 EDT by Adam Mariš
Modified:	2017-04-11 21:59 EDT (History)
CC List:	5 users (show)

See Also:
Fixed In Version:	dovecot 2.2.29
Doc Type:	If docs needed, set a value
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Environment:
Last Closed:	2017-04-11 01:44:56 EDT
Type:	---
Regression:	---
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oVirt Team:	---
RHEL 7.3 requirements from Atomic Host:
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Description Adam Mariš 2017-04-04 03:50:15 EDT

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 03:50:22 EDT

Acknowledgments:

Name: the Dovecot project

Comment 5 Doran Moppert 2017-04-11 21:58:46 EDT

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 2017-04-11 21:58:58 EDT

Statement:

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

Comment 7 Doran Moppert 2017-04-11 21:59:28 EDT

Created dovecot tracking bugs for this issue:

Affects: fedora-all [bug 1441457]

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