Today’s graph charts the percentage of Firefox users who have known-insecure versions of Flash. It also allows us to visually see the impact of various plugin blocks that have been staged over the past few months.

We are gradually rolling out blocks for more and more versions of Flash. In order to make sure that the blocklist was not causing significant user pain, we started out with the oldest versions of Flash that have the fewest users. We have since been expanding the block to include more recent versions of Flash that are still insecure. We hope to extend these blocks to all insecure versions of Flash in the next few months.

From the data, we see that users on very old versions of Flash (Flash 10.2 and earlier) are not changing their behavior because of the blocklist. This either means that the users never see Flash content, or that they always click through the warning. It is also possible that they attempted to upgrade but for some reason are unable.

Users with slightly newer versions seem more likely to upgrade. Over about a month, almost half of the users who had insecure versions of Flash 10.3-11.2 have upgraded.

Finally, it is interesting that these percentages drop down on the weekends. This indicates that work or school computers are more likely to have insecure versions of Flash than home computers. Because there are well-known exploits for all of these Flash versions, this represents a significant risk to organizations who are not keeping up with security updates!

View the chart in HTML version and the raw data. This data was brought to you by Telemetry, and so the standard cautions apply: telemetry is an opt-in sample on the beta/release channels, and may under-represent certain populations, especially enterprise deployments which may lock telemetry off by default. This data represents Windows users only, because we just recently started collecting Flash version information on Mac, and the Linux Flash player doesn’t expose its version at all.

Raw aggregates for Flash usage can be found in my dated directories on crash-analysis.mozilla.com, for example yesterday’s aggregate counts. You are welcome to scrape this data if you want to play with it; I am also willing to provide interested researchers with additional data dumps on request.