[原文]FreeBSD 4.3 does not properly clear shared signal handlers when executing a process, which allows local users to gain privileges by calling rfork with a shared signal handler, having the child process execute a setuid program, and sending a signal to the child.
FreeBSD contains a flaw that may allow a malicious user to gain access to unauthorized privileges. The issue is triggered when a malicious user calls exec() and rfork(RFPROC|RFSIGSHARE) fails to prevent signal handlers from being shared in other processes. This flaw may lead to a loss of integrity.
Upgrade to version 4.3-STABLE after the correction date, as it has been reported to fix this vulnerability. Also, FreeBSD has released a patch.