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Category:   Device (Embedded Server/Appliance)  >   Cisco Hosting Solution Engine Vendors:   Cisco
(Cisco Hosting Solution Engine is Vulnerable) 'zlib' Shared Compression Library Contains 'Double Free()' Buffer Overflow That Lets Remote Users Cause Programs Using zlib to Crash or Execute Arbitrary Code
SecurityTracker Alert ID:  1003973
SecurityTracker URL:
CVE Reference:   CVE-2002-0059   (Links to External Site)
Date:  Apr 4 2002
Impact:   Denial of service via network, Execution of arbitrary code via local system, Execution of arbitrary code via network
Fix Available:  Yes  Vendor Confirmed:  Yes  
Version(s): 1.0, 1.3
Description:   A vulnerability was reported in the zlib shared library, a widely used library that provides in-memory compress and decompression functions. A remote user could cause programs using this library to crash or to execute arbitrary code on the system.

It is reported that certain types of input will cause zlib to free the same area of memory twice (i.e., perform a "double free"), resulting in a buffer overflow condition when expanding compressed input. A remote user can cause programs that process untrusted user-supplied compressed input to crash or potentially execute arbitrary code on the system.

Cisco reports that certain versions of Cisco's Hosting Solution Engine are vulnerable because they use the affected zlib library. The following versions are vulnerable: 1.0 and 1.3.

It is reported that Matthias Clasen <> and Owen Taylor <> discovered this bug in zlib.

Impact:   A remote user can cause affected programs that use zlib to process untrusted user-supplied compressed input to crash or potentially execute arbitrary code on the system.
Solution:   Release 1.4 contains the fix. It will be available on April 15, 2002, according to Cisco.
Vendor URL: (Links to External Site)
Cause:   Boundary error

Message History:   This archive entry is a follow-up to the message listed below.
Mar 11 2002 'zlib' Shared Compression Library Contains 'Double Free()' Buffer Overflow That Lets Remote Users Cause Programs Using zlib to Crash or Execute Arbitrary Code

 Source Message Contents

Subject:  Cisco Security Advisory: Vulnerability in zlib library


Cisco Security Advisory: Vulnerability in the zlib Compression Library

Revision 1.0

For Public Release 2002 April 03 16:00 (UTC +0000)

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    Affected Products
    Software Versions and Fixes
    Obtaining Fixed Software
    Exploitation and Public Announcements
    Status of This Notice
    Revision History
    Cisco Security Procedures

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There is a vulnerability in the zlib compression library. This code is used
in multiple applications. While we have not identified any Cisco product
that is directly impacted by the vulnerability, there are several products
that are using third-party modules that are vulnerable or that are running
on an operating system that is vulnerable. This vulnerability has been
publicly disclosed.

Cisco PSIRT is still evaluating which products are affected by this

There is no workaround for this vulnerability.

This advisory is available at

Affected Products
The following products are affected:

Cache Software/ACNS
      + Content Engine 507, 560, 590, and 7320 running Cache Software 3.1.1
        or Application and Content Networking Software 4.0.x or 4.1.1
      + Content Router 4430 and Content Distribution Manager 4630 and 4650
        running Application and Content Networking Software 4.0.x or 4.1.1

    This product reached the end-of-life state in 2001. This product is no
    longer supported, and customers are strongly advised to migrate to a
    recent product.

Cisco Intrusion Detection System
    Cisco IDS sensor appliances (part numbers IDS-4210, IDS-4220-E and
    IDS-4230-xx) are vulnerable if the sensor version as reported by nrvers
    is in the range 3.0(1) through 3.0(5) inclusive. The C6000 IDSM (part
    number WS-X6381-IDS) is not vulnerable.

Metro 1500 DWDM
    All releases prior the software release 3.3b.

Hosting Solution Engine (HSE)
    HSE releases 1.0 and 1.3 are vulnerable.

We are still evaluating the rest of Cisco products against this

We have verified that the following products are not vulnerable or that
exposure is negligible. Note that this is not an exhaustive list.

  * Cisco CatOS
  * Cisco SN 5420 Storage Routers
  * PIX Firewall
  * VPN 3000, 3500
  * User Registration Tool (URT)

Some products, such as Cisco IOS, use compressed images. In order to
utilize this attack vector, an attacker would have to prepare a tampered
distribution image and try to load it onto a device. That implies either
physical or administrative access to the device. By having such access, an
attacker is in a position to execute many other attacks, some of which are
much easier to accomplish. Although Cisco will incorporate the fixed
version of zlib in the subsequent software releases for products that
belong to this category, that fact will not be reflected in this advisory.

There is a bug in the decompression algorithm used by the popular zlib
compression library. By sending a crafted block of invalid compressed data,
an attacker can cause the application to corrupt internal data. This
happens when the application tries to uncompress the data.

In most cases this vulnerability will cause denial of service. However,
depending on the right circumstances and applications, there is a potential
that an attacker could execute an arbitrary code. This code would then be
executed using the privileges of the application in question.

By repeatedly exploiting this vulnerability, an attacker can cause denial
of service. It is possible that an attacker may be able to execute an
arbitrary code on the target machine. In that case, this may lead to a
partial or total compromise of the machine in question.

Software Versions and Fixes
Cache Software/ACNS
    ACNS 4.1.3 is the fixed release. It will be available in the second
    half of April 2002.

    This product has reached the end-of-life state and the fix is not
    scheduled. Customers are strongly advised to migrate to a recent

Cisco Intrusion Detection System
    Sensor appliance software version 3.1(1) is the first fixed release. It
    will be available on April 16, 2002.

Metro 1500 DWDM
    The software release 3.3b is the first fixed release. It will be
    available on April 5, 2002.

Hosting Solution Engine
    HSE release 1.4 contains the fix. It will be available on April 15,

Obtaining Fixed Software
Cisco is offering free software upgrades to address this vulnerability for
all affected customers. Customers may only install and expect support for
the feature sets they have purchased.

Customers with service contracts should contact their regular update
channels to obtain any software release containing the feature sets they
have purchased. For most customers with service contracts, this means that
upgrades should be obtained through the Software Center on Cisco's
Worldwide Web site at

Customers whose Cisco products are provided or maintained through prior or
existing agreement with third-party support organizations such as Cisco
Partners, authorized resellers, or service providers should contact that
support organization for assistance with the upgrade.

Customers who purchased directly from Cisco but who do not hold a Cisco
service contract, and customers who purchase through third party vendors
but are unsuccessful at obtaining fixed software through their point of
sale, should obtain fixed software by contacting the Cisco Technical
Assistance Center (TAC). In these cases, customers may only upgrade to a
later version of the same release or as indicated by the applicable entry
in the Software Versions and Fixes section.

  * +1 800 553 2447 (toll-free from within North America)
  * +1 408 526 7209 (toll call from anywhere in the world)
  * e-mail:

See for
additional TAC contact information, including special localized telephone
numbers and instructions and e-mail addresses for use in various languages.

Please have your product serial number available and give the URL of this
notice as evidence of your entitlement to a free upgrade.

Please do not contact either "" or
"" for software upgrades.

There is no workaround for this vulnerability.

Exploitation and Public Announcements
This vulnerability was publicly announced by third parties on March 21,
2002. The related advisories can be found at:


Status of This Notice: INTERIM
This is an interim security advisory. Cisco anticipates issuing updated
versions of this notice at irregular intervals as there are material
changes in the facts, and will continue to update this notice as necessary.
The reader is warned that this notice may contain inaccurate or incomplete
information. Although Cisco cannot guarantee the accuracy of all statements
in this notice, all of the facts have been checked to the best of our
ability. Cisco anticipates issuing monthly updates of this notice until it
reaches FINAL status.

A standalone copy or paraphrase of the text of this security advisory that
omits the distribution URL in the following section is an uncontrolled
copy, and may lack important information or contain factual errors.

This notice will be posted on Cisco's Worldwide Web site at http:// In addition to
Worldwide Web posting, a text version of this notice is clear-signed with
the Cisco PSIRT PGP key and is posted to the following e-mail and Usenet
news recipients:

  * (includes CERT/CC)
  * Various internal Cisco mailing lists

Future updates of this notice, if any, will be placed on Cisco's Worldwide
Web server, but may or may not be actively announced on mailing lists or
newsgroups. Users concerned about this problem are encouraged to check the
URL given above for any updates.

Revision History
|Revision 1.0|2002-April-03 16:00 UTC+0000|Initial public release|

Cisco Security Procedures
Complete information on reporting security vulnerabilities in Cisco
products, obtaining assistance with security incidents, and registering to
receive security information from Cisco, is available on Cisco's Worldwide
Web site at
This includes instructions for press inquiries regarding Cisco security 

All Cisco Security Advisories are available at

- ---------------------------------------------------------------------------

This notice is Copyright 2002 by Cisco Systems, Inc. This notice may be
redistributed freely after the release date given at the top of the text,
provided that redistributed copies are complete and unmodified, and include
all date and version information.

- ---------------------------------------------------------------------------

Version: PGP 6.5.3



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