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Home » Security Advisories» Fedora » Zlib buffer overflows

Zlib buffer overflows

Tavis Ormandy discovered a buffer overflow affecting Zlib version 1.2 and above. An attacker could create a carefully crafted compressed stream that would cause an application to crash if the stream is opened by a user. As an example, an attacker could create a malicious PNG image file which would cause a web browser or mail viewer to crash if the image is viewed. Markus Oberhumer discovered additional ways a stream could trigger an overflow. An attacker could create a carefully crafted compressed stream that would cause an application to crash if the stream is opened by a user. As an example, an attacker could create a malicious PNG image file that would cause a Web browser or mail viewer to crash if the image is viewed.

  • Vendor: Fedora
  • Vendor ID: FLSA:162680
  • Date: September 14, 2005


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Fedora Legacy Update Advisory

Synopsis: Updated Zlib packagea fix security issues
Advisory ID: FLSA:162680
Issue date: 2005-09-14
Product: Fedora Core
Keywords: Bugfix
CVE Names: CAN-2005-1849 CAN-2005-2096
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1. Topic:

Updated Zlib packages that fix buffer overflows are now available.

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

2. Relevant releases/architectures:

Fedora Core 1 - i386
Fedora Core 2 - i386

3. Problem description:

Tavis Ormandy discovered a buffer overflow affecting Zlib version 1.2
and above. An attacker could create a carefully crafted compressed
stream that would cause an application to crash if the stream is opened
by a user. As an example, an attacker could create a malicious PNG image
file which would cause a web browser or mail viewer to crash if the
image is viewed. The Common Vulnerabilities and Exposures project
assigned the name CAN-2005-2096 to this issue.

Markus Oberhumer discovered additional ways a stream could trigger an
overflow. An attacker could create a carefully crafted compressed stream
that would cause an application to crash if the stream is opened by a
user. As an example, an attacker could create a malicious PNG image file
that would cause a Web browser or mail viewer to crash if the image is
viewed. The Common Vulnerabilities and Exposures project (cve.mitre.org)
assigned the name CAN-2005-1849 to this issue.

All users should update to these erratum packages which contain a patch
from Mark Adler which corrects this issue.

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 yum and apt. Many
people find this an easier way to apply updates. To use yum issue:

yum update

or to use apt:

apt-get update; apt-get upgrade

This will start an interactive process that will result in the
appropriate RPMs being upgraded on your system. This assumes that you
have yum or apt-get configured for obtaining Fedora Legacy content.
Please visit http://www.fedoralegacy.org/docs for directions on how to
configure yum and apt-get.

5. Bug IDs fixed:

https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=162680

6. RPMs required:

Fedora Core 1:

SRPM:
http://download.fedoralegacy.org/fedora/1/updates/SRPMS/zlib-1.2.0.7-2.3.legacy.src.rpm

i386:
http://download.fedoralegacy.org/fedora/1/updates/i386/zlib-1.2.0.7-2.3.legacy.i386.rpm
http://download.fedoralegacy.org/fedora/1/updates/i386/zlib-devel-1.2.0.7-2.3.legacy.i386.rpm

Fedora Core 2:

SRPM:
http://download.fedoralegacy.org/fedora/2/updates/SRPMS/zlib-1.2.1.2-0.fc2.2.legacy.src.rpm

i386:
http://download.fedoralegacy.org/fedora/2/updates/i386/zlib-1.2.1.2-0.fc2.2.legacy.i386.rpm
http://download.fedoralegacy.org/fedora/2/updates/i386/zlib-devel-1.2.1.2-0.fc2.2.legacy.i386.rpm


7. Verification:

SHA1 sum Package Name
---------------------------------------------------------------------

f242225e07d39648b0d7d6558150285ddf7f62d8
fedora/1/updates/i386/zlib-1.2.0.7-2.3.legacy.i386.rpm
618d744e5a8f9a895b40f952a8593985c93fd6d6
fedora/1/updates/i386/zlib-devel-1.2.0.7-2.3.legacy.i386.rpm
c812abcd0c5bcfccc86573e81d68ebff5b615ded
fedora/1/updates/SRPMS/zlib-1.2.0.7-2.3.legacy.src.rpm
d07c43de860f476302fcd1fc82d18db1835e1ba1
fedora/2/updates/i386/zlib-1.2.1.2-0.fc2.2.legacy.i386.rpm
f3326c134c6346ca8f120d86d28908ad45907bf9
fedora/2/updates/i386/zlib-devel-1.2.1.2-0.fc2.2.legacy.i386.rpm
2d288f7b2dd848a4c3f36d3ff7c200b9b629c868
fedora/2/updates/SRPMS/zlib-1.2.1.2-0.fc2.2.legacy.src.rpm

These packages are GPG signed by Fedora Legacy for security. Our key is
available from http://www.fedoralegacy.org/about/security.php

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 sha1sum with the following command:

sha1sum

8. References:

http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-1849
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-2096

9. Contact:

The Fedora Legacy security contact is [email protected]>. More
project details at http://www.fedoralegacy.org

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