A US Department of Homeland Security (DHS) bug-fixing scheme has uncovered an average of one security glitch per 1,000 lines of code in 180 widely used open source software projects.

The program, called the Open Source Hardening Project, is sponsored by the DHS and carried out by Coverity and Stanford University. Launched in March 2006, the US$300,000 project was initially launched to review the code of 180 open source software projects frequently used by developers of government websites and application developers.

All the software scrutinized was found to have significant numbers of security flaws, Coverity said on Wednesday. Since 2006 the project has helped fix 7,826 open source flaws in 250 projects, out of 50 million lines of code scanned, the company said.

Coverity also scans proprietary software, handling about 400 product lines for private customers, but said its private clients don't tend to disclose information about bugs found in their products.

Many of the open source projects scanned have been assiduous in repairing the bugs that have turned up, and on Wednesday Coverity advanced the first batch of 11 open source projects to its second stage of the bug-cleansing process, called Rung 2. Many more remain on Rung 1 or even Rung 0, meaning they haven't yet begun to fix the flaws identified.

The 11 projects are Amanda, NTP, OpenPAM, OpenVPN, Overdose, Perl, PHP, Postfix, Python, Samba, and TCL. Other popular software the project has scrutinized include Apache, the Linux kernel and Firefox.

Rung 2 is the highest security level yet reached under the DHS project, and was attained by eliminating several classes of security and quality defects, according to Coverity open source strategist David Maxwell.

For instance, 236 flaws were uncovered in 450,000 lines of Samba code, of which 228 have been corrected.

Having passed to the next level, Coverity will provide the projects with an updated version of its scanner product, which will allow developers to identify still more flaws.

The Rung 2 scanning service will be upgraded from version 2.4 to version 3.6 of Coverity's Prevent bug-scanning product, Coverity said. The latest version in commercial use is 3.8.

The bug checks are carried out via Coverity's Scan website.