[ GLSA 200606-19 ] Sendmail: Denial of Service

[GLSA]

Gentoo Linux Security Advisory

Title: Sendmail: Denial of Service (GLSA 200606-19)
Severity: normal
Exploitable: remote
Date: June 15, 2006
Bug(s): #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: mail-mta/sendmail
Vulnerable: < 8.13.6-r1
Unaffected: >= 8.13.6-r1
Architectures: 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: