GLSA 200606-19: Sendmail: Denial of Service

http://security.gentoo.org/

Severity:	normal
Title:	Sendmail: Denial of Service
Date:	06/15/2006
Bugs:	#135141
ID:	200606-19

Synopsis

Faulty multipart MIME messages can cause forked Sendmail processes to crash.

Background

Sendmail is a popular mail transfer agent (MTA).

Affected packages

Package	Vulnerable	Unaffected	Architecture(s)
mail-mta/sendmail	< 8.13.6-r1	>= 8.13.6-r1	All supported architectures

Description

Frank Sheiness discovered that the mime8to7() function can recurse endlessly during the decoding of multipart MIME messages until the stack of the process is filled and the process crashes.

Impact

By sending specially crafted multipart MIME messages, a remote attacker can cause a subprocess forked by Sendmail to crash. If Sendmail is not set to use a randomized queue processing, the attack will effectively halt the delivery of queued mails as well as the malformed one, incoming mail delivered interactively is not affected. Additionally, on systems where core dumps with an individual naming scheme (like "core.pid") are enabled, a filesystem may fill up with core dumps. Core dumps are disabled by default in Gentoo.

Workaround

The Sendmail 8.13.7 release information offers some workarounds, please see the Reference below. Note that the issue has actually been fixed in the 8.13.6-r1 ebuild.

Resolution

All Sendmail users should upgrade to the latest version:

    # emerge --sync
    # emerge --ask --oneshot --verbose ">=mail-mta/sendmail-8.13.6-r1"

References

Availability

This GLSA and any updates to it are available for viewing at the Gentoo Security Website: http://security.gentoo.org/glsa/glsa-200606-19.xml

Concerns?

Security is a primary focus of Gentoo Linux and ensuring the confidentiality and security of our users machines is of utmost importance to us. Any security concerns should be addressed to security@gentoo.org or alternatively, you may file a bug at https://bugs.gentoo.org.