The Sun RPC functionality in multiple libc implementations does not provide a time-out mechanism when reading data from TCP connections, which allows remote attackers to cause a denial of service (hang).

The unsetenv function in glibc 2.1.1 does not properly unset an environmental variable if the variable is provided twice to a program, which could allow local users to execute arbitrary commands in setuid programs by specifying their own duplicate environmental variables such as LD_PRELOAD or LD_LIBRARY_PATH.

The resolver in glibc 2.1.3 uses predictable IDs, which allows a local attacker to spoof DNS query results.