-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 ============================================================================= FreeBSD-SA-05:18.zlib Security Advisory The FreeBSD Project Topic: Buffer overflow in zlib Category: core Module: libz Announced: 2005-07-27 Credits: Markus Oberhumer Affects: FreeBSD 5.3, FreeBSD 5.4 Corrected: 2005-07-27 08:41:44 UTC (RELENG_6, 6.0-BETA2) 2005-07-27 08:41:56 UTC (RELENG_5, 5.4-STABLE) 2005-07-27 08:42:16 UTC (RELENG_5_4, 5.4-RELEASE-p6) 2005-07-27 08:42:38 UTC (RELENG_5_3, 5.3-RELEASE-p20) CVE Name: CAN-2005-1849 For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit . NOTE WELL: The issue discussed in this advisory is distinct from the issue discussed in the earlier advisory FreeBSD-SA-05:16.zlib, although the impact is very similar. I. Background zlib is a compression library used by numerous applications to provide data compression/decompression routines. II. Problem Description A fixed-size buffer is used in the decompression of data streams. Due to erronous analysis performed when zlib was written, this buffer, which was belived to be sufficiently large to handle any possible input stream, is in fact too small. III. Impact A carefully constructed compressed data stream can result in zlib overwriting some data structures. This may cause applications to halt, resulting in a denial of service; or it may result in an 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 patches have been verified to apply to FreeBSD 5.3, and 5.4 systems. a) Download the relevant patch from the location below, and verify the detached PGP signature using your PGP utility. # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:18/zlib.patch # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:18/zlib.patch.asc 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 Path - ------------------------------------------------------------------------- RELENG_5 src/lib/libz/inftrees.h 1.1.1.5.2.1 RELENG_5_4 src/UPDATING 1.342.2.24.2.15 src/sys/conf/newvers.sh 1.62.2.18.2.11 src/lib/libz/inftrees.h 1.1.1.5.6.1 RELENG_5_3 src/UPDATING 1.342.2.13.2.23 src/sys/conf/newvers.sh 1.62.2.15.2.25 src/lib/libz/inftrees.h 1.1.1.5.4.1 RELENG_6 src/lib/libz/inftrees.h 1.1.1.5.8.1 - ------------------------------------------------------------------------- VII. References http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-1849 The latest revision of this advisory is available at ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-05:18.zlib.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (FreeBSD) iD4DBQFC50oLFdaIBMps37IRAg/1AJjTCluaNxJuBbSalLtgF34iey8DAJ9BGJmr 9NNdJfcjbm4qucvUYdsOqA== =XDop -----END PGP SIGNATURE-----