Note: This is an archival copy of Security Sun Alert 275870 as previously published on
Latest version of this security advisory is available from as Sun Alert 1021797.1.
Article ID : 1021797.1
Article Type : Sun Alerts (SURE)
Last reviewed : 2010-06-07
Audience : PUBLIC
Copyright Notice: Copyright © 2010, Oracle Corporation and/or its affiliates.

A Security Vulnerability Relating to Certificate Handling in sendmail(1M) Versions Prior to 8.14.4 May Allow Server Identification Forgery


Release Phase

In this Document
  Likelihood of Occurrence
  Possible Symptoms
  Workaround or Resolution
  Modification History

Applies to:

OpenSolaris Operating System - Version: All Versions and later   [Release: and later ]
Sun Software > Operating Systems > Solaris Operating System
SUNBUG 6913961


A security vulnerability related to X.509 certificates affects sendmail(1M) as shipped with Solaris. This vulnerability may allow a remote user who controls a server which communicates with sendmail in some way (either as a client or another server), to present a crafted certificate which would appear to have come from any system on the Internet, and would be incorrectly accepted as valid by sendmail.

Exploitation of this issue is considered difficult and would typically require redirecting sendmail to an incorrect server by some means such as leveraging an exploit in DNS. The specific impact would depend on the way sendmail is configured to use the X.509 certificates.

For example, if sendmail is configured to require that mail being sent to a certain domain will only be delivered to that domain's mail server if it has a valid certificate for that domain, then it may be possible for a remote user to impersonate that server by presenting a forged certificate. The remote user would first have to cause sendmail to connect to a server which he or she controls instead of the correct one.

This issue is also discussed in the following documents:

CVE 2009-4565 at


Likelihood of Occurrence

This issue can occur in the following releases:

SPARC Platform
  • Solaris 10 with patch 120302-01 or later
  • OpenSolaris based upon builds snv_13 through snv_131
x86 Platform
  • Solaris 10 with patch 120303-01 or later
  • OpenSolaris based upon builds snv_13 through snv_131

1. This issue only affects systems on which sendmail has been configured to use TLS with X.509 certificates. To determine if sendmail is running on a host and whether TLS is enabled, the mconnect(1) command can be used to connect to sendmail (if running), after which, the EHLO command will output the supported extensions.

For example:
$ mconnect mailserver
connecting to host mailserver (, port 25
connection open
220 ESMTP Sendmail 8.14.3+Sun/8.14.3; Mon, 18 Jan 2010 14:29:31 -0800ST)
EHLO Hello localhost [], pleased to meet you
If "STARTTLS" appears in the list of supported extensions, the sendmail server may be vulnerable.

The sendmail configuration would determine how the certificates are used, and therefore what may be achieved by a user presenting a forged certificate. See the sendmail documentation for more information, for example, the file /etc/mail/cf/README under the heading 'STARTTLS'.

If sendmail is not running on the system the mconnect(1) command will report the following:
$ /usr/bin/mconnect
connecting to host localhost (, port 25
connect: Connection refused
2. Sendmail shipped with Solaris 8 and 9 does not support TLS and those releases are not impacted.

Possible Symptoms

There are no predictable symptoms that would indicate that a forged certificate has been used with sendmail.

Workaround or Resolution

This issue is resolved in the following releases:

SPARC Platform

  • Solaris 10 with patch 142436-04 or later
  • OpenSolaris based upon builds snv_132 or later
x86 Platform
  • Solaris 10 with patch 142437-04 or later
  • OpenSolaris based upon builds snv_132 or later



Modification History

07-Jun-2010 - Updated for patch release, issue is Resolved


<PATCH:142437-04> -
sunpatch 142436-04

This solution has no attachment