Gallery before 1.5.9, and 2.x before 2.2.6, does not set the secure flag for the session cookie in an https session, which can cause the cookie to be sent in http requests and make it easier for remote attackers to capture this cookie.
https://www.redhat.com/archives/fedora-package-announce/2008-December/msg00832.html
https://www.redhat.com/archives/fedora-package-announce/2008-December/msg00794.html
http://www.securityfocus.com/bid/31231
http://www.securityfocus.com/archive/1/496509/100/0/threaded
http://security.gentoo.org/glsa/glsa-200811-02.xml
http://secunia.com/advisories/33144
http://secunia.com/advisories/32662
http://seclists.org/fulldisclosure/2008/Sep/0379.html
http://int21.de/cve/CVE-2008-3662-gallery.html