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Home » Hacking News » RedHat RHSA-2003:079-01: zlib buffer overflow

RedHat RHSA-2003:079-01: zlib buffer overflow

by Nikola Strahija on April 30th, 2003 Zlib library has a buffer overflow vulnerability which can be used by attackers to cause a denial of service or execution of arbitrary code.

Red Hat Security Advisory

Synopsis: Updated zlib packages fix gzprintf buffer overflow vulnerability
Advisory ID: RHSA-2003:079-01
Issue date: 2003-04-29
Updated on: 2003-04-29
Product: Red Hat Linux
Keywords: gzprintf buffer overflow
Cross references:
CVE Names: CAN-2003-0107

1. Topic:

Updated zlib packages are now available which fix a buffer overflow

2. Relevant releases/architectures:

Red Hat Linux 7.1 - i386
Red Hat Linux 7.2 - i386, ia64
Red Hat Linux 7.3 - i386
Red Hat Linux 8.0 - i386

3. Problem description:

Zlib is a general-purpose, patent-free, lossless data compression
library used by many different programs.

The function gzprintf within zlib, when called with a string longer than
Z_PRINTF_BUFZISE (= 4096 bytes), can overflow without giving a warning.

zlib-1.1.4 and earlier exhibit this behavior. There are no known exploits
of the gzprintf overrun, and only a few programs, including rpm2html
and gimp-print, are known to use the gzprintf function.

The problem has been fixed by checking the length of the output string
within gzprintf.

4. Solution:

Before applying this update, make sure all previously released errata
relevant to your system have been applied.

To update all RPMs for your particular architecture, run:

rpm -Fvh [filenames]

where [filenames] is a list of the RPMs you wish to upgrade. Only those
RPMs which are currently installed will be updated. Those RPMs which are
not installed but included in the list will not be updated. Note that you
can also use wildcards (*.rpm) if your current directory *only* contains the
desired RPMs.

Please note that this update is also available via Red Hat Network. Many
people find this an easier way to apply updates. To use Red Hat Network,
launch the Red Hat Update Agent with the following command:


This will start an interactive process that will result in the appropriate
RPMs being upgraded on your system.

5. Bug IDs fixed ( for more info):

84961 - buffer overrun on gzprintf

6. RPMs required:

Red Hat Linux 7.1:



Red Hat Linux 7.2:




Red Hat Linux 7.3:



Red Hat Linux 8.0:



7. Verification:

MD5 sum Package Name
2a540854e1b366583f46f2cb9d12d76a 7.1/en/os/SRPMS/zlib-1.1.4-8.7x.src.rpm
c364711c074bbb9c6fb9c81d5c183c04 7.1/en/os/i386/zlib-1.1.4-8.7x.i386.rpm
aeb4221c4d816c8d750f993051c4e9da 7.1/en/os/i386/zlib-devel-1.1.4-8.7x.i386.rpm
2a540854e1b366583f46f2cb9d12d76a 7.2/en/os/SRPMS/zlib-1.1.4-8.7x.src.rpm
c364711c074bbb9c6fb9c81d5c183c04 7.2/en/os/i386/zlib-1.1.4-8.7x.i386.rpm
aeb4221c4d816c8d750f993051c4e9da 7.2/en/os/i386/zlib-devel-1.1.4-8.7x.i386.rpm
654a4dd09a48b3524ddd3b721e6407c2 7.2/en/os/ia64/zlib-1.1.4-8.7x.ia64.rpm
bd9506cf823b2888459844d3e4998be7 7.2/en/os/ia64/zlib-devel-1.1.4-8.7x.ia64.rpm
2a540854e1b366583f46f2cb9d12d76a 7.3/en/os/SRPMS/zlib-1.1.4-8.7x.src.rpm
c364711c074bbb9c6fb9c81d5c183c04 7.3/en/os/i386/zlib-1.1.4-8.7x.i386.rpm
aeb4221c4d816c8d750f993051c4e9da 7.3/en/os/i386/zlib-devel-1.1.4-8.7x.i386.rpm
fe4170379794e81a2609fa7e71310588 8.0/en/os/SRPMS/zlib-1.1.4-8.8x.src.rpm
fb1db2a01b5366cb40f98fda4507024e 8.0/en/os/i386/zlib-1.1.4-8.8x.i386.rpm
9b4caed6d7487dbd65897b4932403dc7 8.0/en/os/i386/zlib-devel-1.1.4-8.8x.i386.rpm

These packages are GPG signed by Red Hat for security. Our key is
available at

You can verify each package with the following command:

rpm --checksig -v

If you only wish to verify that each package has not been corrupted or
tampered with, examine only the md5sum with the following command:


8. References:

9. Contact:

The Red Hat security contact is . More contact
details at

Copyright 2003 Red Hat, Inc.

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