PHP before 5.4.40, 5.5.x before 5.5.24, and 5.6.x before 5.6.8 does not ensure that pathnames lack %00 sequences, which might allow remote attackers to read arbitrary files via crafted input to an application that calls the stream_resolve_include_path function in ext/standard/streamsfuncs.c, as demonstrated by a filename\0.extension attack that bypasses an intended configuration in which client users may read files with only one specific extension.