When using overly long filenames or field names, a memory limit could be hit which results in stopping the upload but not cleaning up behind. This could lead to exhausted disk space on the server.
For Debian 7 Wheezy, these problems have been fixed in version 5.4.45-0+deb7u30.
We recommend that you upgrade your php5 packages.
Further information about Extended LTS security advisories can be found at: https://deb.freexian.com/extended-lts/