Buffer overflow in zlib

Insufficient checking in the zlib compression library (installed
as libz on OpenBSD) can result in a buffer overflow and a program
crash.  It is not known at this time whether maliciously-crafted
compressed files can be used to execute arbitrary code.

Since zlib is in wide use throughout the base OS, as well as in
ports, users are advised to patch their systems as soon as possible.

A fix has been committed to OpenBSD-current as well as the 3.6 and
3.7 -stable branches.  Patches are also available for OpenBSD 3.6
and 3.7.  OpenBSD versions 3.4 and lower are not affected as they
use an older version of zlib that does not contain the vulnerable
code.

3.6 patch:  
    ftp://ftp.openbsd.org/pub/OpenBSD/patches/3.6/common/019_libz.patch
3.7 patch:
    ftp://ftp.openbsd.org/pub/OpenBSD/patches/3.7/common/004_libz.patch

The 3.6 patch also applies to OpenBSD 3.5.