Nagios is an open source host, service and network monitoring program.
Sebastian Krahmer of the SuSE security team discovered a buffer overflow vulnerability in the handling of a negative HTTP Content-Length header.
A buffer overflow in Nagios CGI scripts under certain web servers allows remote attackers to execute arbitrary code via a negative content length HTTP header.
There is no known workaround at this time.
All Nagios users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=net-analyzer/nagios-core-1.4.1"