An off-by-one error exists in the C library function realpath(3). This is the same bug that was recently found in the wu-ftpd ftpd server by Janusz Niewiadomski and Janusz Niewiadomski.
Credit:
The information has been provided by Todd C. Miller.
The OpenBSD ftp daemon does not use realpath(3) in a way that could be exploited, however a number of other system binaries also use the function. It is not currently known whether this bug results in an exploitable security hole on OpenBSD. Since the bug led to an exploitable hole in wu-ftpd, it is entirely possible that some program using realpath(3) under OpenBSD may be vulnerable to attack. For OpenBSD 3.3 and higher, the ProPolice stack protector should provide some protection from this bug, but this cannot be guaranteed.
This bug has been fixed in OpenBSD-current as well as the 3.2 and 3.3 stable branches. Patches are available for OpenBSD 3.2 and 3.3.
