The NFSv4 ID mapper (nfsidmap) before 0.17 does not properly handle return values from the getpwnam_r function when performing a username lookup, which can cause it to report a file as being owned by "root" instead of "nobody" if the file exists on the server but not on the client.
http://secunia.com/advisories/26674
http://secunia.com/advisories/27043
https://exchange.xforce.ibmcloud.com/vulnerabilities/36396
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A9864
http://www.mandriva.com/security/advisories?name=MDKSA-2007:240
http://www.novell.com/linux/security/advisories/2007_18_sr.html