Bug 702474 (CVE-2011-1764)

Summary:	CVE-2011-1764 exim: improper format string handling in DKIM signatures
Product:	[Other] Security Response	Reporter:	Vincent Danen <vdanen>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED CURRENTRELEASE	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	bressers, dwmw2, jskarvad, mlichvar
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	exim 4.76	Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2012-08-10 18:36:33 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:	702475, 705448
Bug Blocks:

Description Vincent Danen 2011-05-05 18:40:26 UTC

It was reported [1],[2] that Exim would improperly interpret '%' in a DKIM (DomainKeys Identified Mail) signature, which would get logged to the paniclog.  It is possible that using '%n' in the DKIM signature could be used to verwrite stack data, which could cause Exim to crash.

DKIM support has been in Exim since version 4.70.

A fix has been pushed upstream [3].

[1] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=624670
[2] http://bugs.exim.org/show_bug.cgi?id=1106
[3] http://git.exim.org/exim.git/commitdiff/337e3505b0e6cd4309db6bf6062b33fa56e06cf8


Statement:

Not vulnerable. This issue did not affect the versions of exim as shipped with Red Hat Enterprise Linux 4 or 5 as they did not include support for DKIM.

Comment 1 Vincent Danen 2011-05-05 18:41:13 UTC

Created exim tracking bugs for this issue

Affects: fedora-all [bug 702475]

Comment 2 Josh Bressers 2011-05-05 18:49:35 UTC

A workaround is to add "control = dkim_disable_verify" to an ACL to prevent processing DKIM signatures.

Comment 3 Vincent Danen 2011-05-17 17:54:24 UTC

Created exim tracking bugs for this issue

Affects: epel-6 [bug 705448]

Comment 4 Vincent Danen 2012-08-10 18:23:54 UTC

According to:

http://wiki.exim.org/EximSecurity

This was resolved in upstream 4.76.  Current supported versions of Fedora provide 4.76, however EPEL6 still provides 4.72 and is still vulnerable.

Comment 5 Vincent Danen 2012-08-10 18:36:33 UTC

It seems that EPEL6 did fix this, but incorrectly noted the wrong CVE:

exim-4.72-0003-CVE-2011-1407.patch is from the git commit above, so it actually fixes CVE-2011-1764 and _not_ CVE-2011-1407 as the patch name and changelog implied.