tl;dr: Open Source is inherently no more or less secure than closed source software.
For a more thorough answer to this question, we’ve just updated our briefing note, “Is Open Source Software Insecure? An Introduction To The Issues” where we look at some of the ways in which software is considered secure, and look at some of the common claims both for and against the security of Free & Open Source Software.
On the whole there are no significant differences in security between closed and open source software as a category. The key differences are between individual products, and the governance processes around security – something which applies to both closed and open source software.
Claims that Open Source is inherently insecure – or, conversely, that it is inherently more secure – are unfounded and should be challenged, particularly in the process of selecting and procuring software. Accepting such a generalisation may actually be increasing security risks for the organisation, by excluding the most fit-for-purpose solutions from consideration.
Photo by nolifebeforecoffee of a stencil by banksy.