Remote vulnerability in Posadis 0.50.x
======================================

Products affected
-----------------

Posadis DNS server, all platforms, versions 0.50.4 through 0.50.8

Not affected
------------

 - Posadis DNS server, Milestone 5 and earlier; versions 0.50.9 and later, or
   version 0.50.8 with the bugfix patch applied.
 - Poslib DNS library and applications using it, such as the Simple Authoritive
   Name Server and Pos6, the unstable 0.60.x series of Posadis.

Details
-------

Posadis versions 0.50.4 through 0.50.8 contain a bug, causing them not to
properly check whether specific DNS messages contain a question section. Thus,
Posadis might try to read from a NULL memory location. This bug, which was
discovered in an internal test, allows any person to crash the DNS server by
sending a malformed packet to it. Since operating systems should not let an
application read from NULL, this bug would always let Posadis crash. Therefore,
the bug can, as we sincerely believe, not be used to take over control of your
machine.

Solution
--------

Users of Posadis 0.50.8 and earlier should upgrade as soon as possible, either
to Posadis 0.50.9 or later, or using one of the following (these files are
available on www.posadis.org/files/):

 - Download a new source tarball: posadis-0.50.8a.tar.gz
   (md5sum a98f3075d425eb8d87685da13c2d01a6)
 - Download a patch for the Posadis 0.50.8 sources:
   pos-0.50.8-fix (md5sum f38026481ee946cc9755b742211b3582)
 - Download a new Posadis binary for Linux: posadis-0.50.8-fixed
   (md5sumd3d92e7871e532a5cee6ecb33136bfa6)
 - Download a new Posadis binary for Windows: posadis-0.50.8-fixed.exe
   (md5sum 17e35a56934e372db3f3249e1e8a1af4)

This patch is cumulative; it also contains the recently discovered FreeBSD
build fixes, and some small standards compliance fixes.

SecurityFocus article
---------------------

A SecurityFocus article about this bug can be read here:
  http://www.securityfocus.com/bid/6799