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Category:   Application (Multimedia)  >   libpng Vendors:
(Apple Issues Fix) libpng Memory Access Violation When Creating Error Messages May Cause Denial of Service Conditions
SecurityTracker Alert ID:  1010908
SecurityTracker URL:
CVE Reference:   CVE-2004-0421   (Links to External Site)
Date:  Aug 10 2004
Impact:   Denial of service via network
Fix Available:  Yes  Vendor Confirmed:  Yes  

Description:   A vulnerability was reported in libpng. A remote user can create a PNG image that, when processed by libpng, may cause denial of service conditions.

Mandrake reported that when libpng creates an error message, libpng may access invalid memory locations. As a result, an application using libpng may crash or core dump when processing certain PNG images, the report said.

Steve Grubb is credited with discovering this flaw.

Impact:   A remote user can create a malformed PNG image that, when processed by an application using libpng, may cause the application to crash. The specific impact depends on the application using libpng.
Solution:   Apple has issued a fix as part of Mac OS X 10.3.5, available via the Software Update pane in System Preferences or Apple's Software Downloads web site at:

Vendor URL: (Links to External Site)
Cause:   Access control error, Resource error
Underlying OS:  UNIX (macOS/OS X)
Underlying OS Comments:  10.3.4 and prior versions

Message History:   This archive entry is a follow-up to the message listed below.
Apr 30 2004 libpng Memory Access Violation When Creating Error Messages May Cause Denial of Service Conditions

 Source Message Contents

Subject:  APPLE-SA-2004-08-09 Mac OS X 10.3.5

Hash: SHA1

APPLE-SA-2004-09-09 Mac OS X 10.3.5

Mac OS X 10.3.5 is now available and delivers security enhancements
for the following components:

Component:  libpng (Portable Network Graphics)
CVE-IDs:    CAN-2002-1363, CAN-2004-0421, CAN-2004-0597,
CAN-2004-0598, CAN-2004-0599
Impact:  Malicious png images can cause application crashes and could
execute arbitrary code

Description:  A number of buffer overflows, null pointer dereferences
and integer overflows have been discovered in the reference library
for reading and writing PNG images. These vulnerabilities have been
corrected in libpng which is used by the CoreGraphics and AppKit
frameworks in Mac OS X.  After installing this update, applications
that use the PNG image format via these frameworks will be protected
against these flaws.

Note:  The libpng security fixes are also available separately for Mac
OS X 10.3.4 and Mac OS X 10.2.8 via Security Update 2004-08-09.


Component:  Safari
CVE ID:     CAN-2004-0743
Impact: In a special situation, navigation using the forward/backward
buttons can re-send form data to a GET url.

Description:  This is for a situation where a web form is sent to a
server using a POST method which issues an HTTP redirect to a GET
method url.  Using the forward/backward buttons will cause Safari to
re-POST the form data to the GET url.  Safari has been modified so
that in this situation forward/backward navigation will result in only
a GET method.


Component:  TCP/IP Networking
CVE ID:     CAN-2004-0744
Impact:     Maliciously crafted IP fragments can use too many system
resources preventing normal network operation.

Description:  The "Rose Attack" describes a specially constructed
sequence of IP fragments designed to consume system resources.  The
TCP/IP implementation has been modified to limit the resources
consumed and prevents this denial of service attack.


Mac OS X 10.3.5 may be obtained from the Software Update
pane in System Preferences, or Apple's Software Downloads web site:

Information will also be posted to the Apple Product Security
web site:

This message is signed with Apple's Product Security PGP key,
and details are available at:

Version: PGP 8.1

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