Thanks to Mehran for sending this in. OpenBSD IPSEC stack has backdoor and due to that's first open source implementation of ipsec, some OSes have the same piece of code! Since we had the first IPSEC stack available for free, large parts of the code are now found in many other projects/products. Over 10 years, the IPSEC code has gone through many changes and fixes, so it is unclear what the true impact of these allegations are."

The link for this article located at OpenBSD Tech is no longer available.