The feh_unique_filename function in utils.c in feh before 1.11.2 might allow local users to overwrite arbitrary files via a symlink attack on a /tmp/feh_ temporary file.
https://github.com/derf/feh/issues/#issue/32
https://derf.homelinux.org/git/feh/commit/?id=29ab0855f044ef2fe9c295b72abefcb37f0861a5
https://derf.homelinux.org/git/feh/commit/?id=23421a86cc826dd30f3dc4f62057fafb04b3ac40
https://bugzilla.redhat.com/show_bug.cgi?id=676389
https://bugs.launchpad.net/ubuntu/+source/feh/+bug/607328
http://secunia.com/advisories/43221
http://openwall.com/lists/oss-security/2011/02/09/14