FreeBSD 4.x through 4.11 and 5.x through 5.4 allows remote attackers to modify certain TCP options via a TCP packet with the SYN flag set for an already established session.

Multiple TCP implementations with Protection Against Wrapped Sequence Numbers (PAWS) with the timestamps option enabled allow remote attackers to cause a denial of service (connection loss) via a spoofed packet with a large timer value, which causes the host to discard later packets because they appear to be too old.

The kernel in FreeBSD 4.x to 4.11 and 5.x to 5.4 does not properly clear certain fixed-length buffers when copying variable-length data for use by applications, which could allow those applications to read previously used sensitive memory.

The i386_get_ldt system call in FreeBSD 4.7 to 4.11 and 5.x to 5.4 allows local users to access sensitive kernel memory via arguments with negative or very large values.

FreeBSD 4.6 to 4.11 and 5.x to 5.4 uses insecure default permissions for the /dev/iir device, which allows local users to execute restricted ioctl calls to read or modify data on hardware that is controlled by the iir driver.

Race condition in gzip 1.2.4, 1.3.3, and earlier, when decompressing a gzipped file, allows local users to modify permissions of arbitrary files via a hard link attack on a file while it is being decompressed, whose permissions are changed by gzip after the decompression is complete.

The sendfile system call in FreeBSD 4.8 through 4.11 and 5 through 5.4 can transfer portions of kernel memory if a file is truncated while it is being sent, which could allow remote attackers to obtain sensitive information.

The SIOCGIFCONF ioctl (ifconf function) in FreeBSD 4.x through 4.11 and 5.x through 5.4 does not properly clear a buffer before using it, which allows local users to obtain portions of sensitive kernel memory.

Multiple symlink vulnerabilities in portupgrade before 20041226_2 in FreeBSD allow local users to (1) overwrite arbitrary files and possibly replace packages to execute arbitrary code via pkg_fetch, (2) overwrite arbitrary files via temporary files when portupgrade upgrades a port or package, or (3) create arbitrary zero-byte files via the pkgdb.fixme temporary file.

Hyper-Threading technology, as used in FreeBSD and other operating systems that are run on Intel Pentium and other processors, allows local users to use a malicious thread to create covert channels, monitor the execution of other threads, and obtain sensitive information such as cryptographic keys, via a timing attack on memory cache misses.