archive_read_support_format_tar.c in libarchive before 2.2.4 allows user-assisted remote attackers to cause a denial of service (crash) via (1) an end-of-file condition within a tar header that follows a pax extension header or (2) a malformed pax extension header in an (a) PAX or a (b) TAR archive, which results in a NULL pointer dereference, a different issue than CVE-2007-3644.