OSVBD.org is a free and independent repository for detailed information about security exposures and vulnerabilities.
From the “About Us” page:
OSVDB is an independent and open source database created by and for the security community. The goal of the project is to provide accurate, detailed, current, and unbiased technical information on security vulnerabilities. The project will promote greater, more open collaboration between companies and individuals, eliminate redundant works, and reduce expenses inherent with the development and maintenance of in-house vulnerability databases.