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=========================================================== Ubuntu Security Notice USN-127-1 May 17, 2005 bzip2 vulnerabilities CAN-2005-0953, CAN-2005-1260 =========================================================== A security issue affects the following Ubuntu releases: Ubuntu 4.10 (Warty Warthog) Ubuntu 5.04 (Hoary Hedgehog) The following packages are affected: bzip2 libbz2-1.0 The problem can be corrected by upgrading the affected package to version 1.0.2-1ubuntu0.1 (for Ubuntu 4.10), or 1.0.2-2ubuntu0.1 (for Ubuntu 5.04). In general, a standard system upgrade is sufficient to effect the necessary changes. Details follow: Imran Ghory discovered a race condition in the file permission restore code of bunzip2. While a user was decompressing a file, a local attacker with write permissions in the directory of that file could replace the target file with a hard link. This would cause bzip2 to restore the file permissions to the hard link target instead of to the bzip2 output file, which could be exploited to gain read or even write access to files of other users. (CAN-2005-0953) Specially crafted bzip2 archives caused an infinite loop in the decompressor which resulted in an indefinitively large output file ("decompression bomb"). This could be exploited to a Denial of Service attack due to disk space exhaustion on systems which automatically process user supplied bzip2 compressed files. (CAN-2005-1260)