The default configuration of nginx, possibly 1.3.13 and earlier, uses world-readable permissions for the (1) access.log and (2) error.log files, which allows local users to obtain sensitive information by reading the files.
https://github.com/addisonburkett/cve_query_module
https://euvd.enisa.europa.eu/vulnerability/EUVD-2013-0349
http://www.openwall.com/lists/oss-security/2013/02/24/1
http://www.openwall.com/lists/oss-security/2013/02/22/1
http://www.openwall.com/lists/oss-security/2013/02/21/15