The AES-XCBC-MAC algorithm in IPsec in FreeBSD 5.3 and 5.4, when used for authentication without other encryption, uses a constant key instead of the one that was assigned by the system administrator, which can allow remote attackers to spoof packets to establish an IPsec session.

The device file system (devfs) in FreeBSD 5.x does not properly check parameters of the node type when creating a device node, which makes hidden devices available to attackers, who can then bypass restrictions on a jailed process.

ipfw in FreeBSD 5.4, when running on Symmetric Multi-Processor (SMP) or Uni Processor (UP) systems with the PREEMPTION kernel option enabled, does not sufficiently lock certain resources while performing table lookups, which can cause the cache results to be corrupted during multiple concurrent lookups, allowing remote attackers to bypass intended access restrictions.

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.

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.

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.

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.

FreeBSD 5.x to 5.4 on AMD64 does not properly initialize the IO permission bitmap used to allow user access to certain hardware, which allows local users to bypass intended access restrictions to cause a denial of service, obtain sensitive information, and possibly gain privileges.