FreeBSD, Inc. Information for VU#680620

zlib inflate() routine vulnerable to buffer overflow


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Vendor Statement

FreeBSD 5.3 and FreeBSD 5.4 are affected by this issue.  It was addressed in the security advisory FreeBSD-SA-05:16.zlib, which provides instructions on how to correct the problem.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Vendor References



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FreeBSD-SA-05:16.zlib                                       Security Advisory
                                                         The FreeBSD Project

Topic:          Buffer overflow in zlib

Category:       core
Module:         libz
Announced:      2005-07-06
Credits:        Tavis Ormandy
Affects:        FreeBSD 5.3, FreeBSD 5.4
Corrected:      2005-07-06 14:01:11 UTC (RELENG_5, 5.4-STABLE)
               2005-07-06 14:01:30 UTC (RELENG_5_4, 5.4-RELEASE-p4)
               2005-07-06 14:01:52 UTC (RELENG_5_3, 5.3-RELEASE-p18)
CVE Name:       CAN-2005-2096

For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit

I.   Background

zlib is a compression library used by numerous applications to provide
data compression/decompression routines.

II.  Problem Description

An error in the handling of corrupt compressed data streams can result
in a buffer being overflowed.

III. Impact

By carefully crafting a corrupt compressed data stream, an attacker can
overwrite data structures in a zlib-using application.  This may cause
the application to halt, causing a denial of service; or it may result
in the attacker gaining elevated privileges.

IV.  Workaround

No workaround is available.

V.   Solution

Perform one of the following:

1) Upgrade your vulnerable system to 5-STABLE, or to the RELENG_5_4 or
RELENG_5_3 security branch dated after the correction date.

2) To patch your present system:

The following patch has been verified to apply to FreeBSD 5.3 and 5.4

a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.

# fetch
# fetch

b) Execute the following commands as root:

# cd /usr/src
# patch < /path/to/patch
# cd /usr/src/lib/libz/
# make obj && make depend && make && make install

VI.  Correction details

The following list contains the revision numbers of each file that was
corrected in FreeBSD.

Branch                                                           Revision
- -------------------------------------------------------------------------
 src/UPDATING                                            1.342.
 src/UPDATING                                            1.342.
- -------------------------------------------------------------------------

VII. References

The latest revision of this advisory is available at
Version: GnuPG v1.4.1 (FreeBSD)


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