loader/DocumentThreadableLoader.cpp in the XMLHttpRequest implementation in WebCore in WebKit before r58409 does not properly handle credentials during a cross-origin synchronous request, which has unspecified impact and remote attack vectors, aka rdar problem 7905150.
https://bugs.webkit.org/show_bug.cgi?id=37781
http://www.vupen.com/english/advisories/2011/0552
http://www.vupen.com/english/advisories/2011/0212
http://www.vupen.com/english/advisories/2010/2722
http://www.ubuntu.com/usn/USN-1006-1
http://www.securityfocus.com/bid/42494
http://www.mandriva.com/security/advisories?name=MDVSA-2011:039
http://trac.webkit.org/changeset/58409
http://security-tracker.debian.org/tracker/CVE-2010-1760
http://secunia.com/advisories/43068
http://secunia.com/advisories/41856
http://lists.opensuse.org/opensuse-security-announce/2011-01/msg00006.html