Integer overflow in the fts_build function in fts.c in libc in (1) OpenBSD 4.4 and earlier and (2) Microsoft Interix 6.0 build 10.0.6030.0 allows context-dependent attackers to cause a denial of service (application crash) via a deep directory tree, related to the fts_level structure member, as demonstrated by (a) du, (b) rm, (c) chmod, and (d) chgrp on OpenBSD; and (e) SearchIndexer.exe on Vista Enterprise.