Imran Ghory discovered a race condition in the file permission restore code of gzip and gunzip. While a user was compressing or 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 gzip to restore the file permissions to the hard link target instead of to the gzip output file, which could be exploited to gain read or even write access to files of other users. (CAN-2005-0988)
Ulf Harnhammar found a path traversal vulnerability when gunzip was used with the -N option. An attacker could exploit this to create files in an arbitrary directory with the permissions of a user if he tricked this user to decompress a specially crafted gzip file using the -N option (which can also happen in systems that automatically process uploaded gzip files). (CAN-2005-1228)
4 May 2005
A security issue affects these releases of Ubuntu and its derivatives:
Imran Ghory discovered a race condition in the file permission restore code of gzip and gunzip. While a user was compressing or 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 gzip to restore the file permissions to the hard link target instead of to the gzip output file, which could be exploited to gain read or even write access to files of other users. (CAN-2005-0988)
Ulf Harnhammar found a path traversal vulnerability when gunzip was used with the -N option. An attacker could exploit this to create files in an arbitrary directory with the permissions of a user if he tricked this user to decompress a specially crafted gzip file using the -N option (which can also happen in systems that automatically process uploaded gzip files). (CAN-2005-1228)
The problem can be corrected by updating your system to the following package versions:
To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.
Vulmon