Snort is preparing to EOL the following versions of Snort rules on Dec. 18. External third-party vendors that are on 2.9.11.1 can’t upgrade just yet. There are still about 42,000 users on those two versions, so we urge everyone on that two versions to upgrade as soon as possible. We are also planning on releasing bug fix 2.15.1 (tentatively) and a larger release of 29.16.0 in April 2020.”]
Source: https://blog.snort.org/2019/12/snort-version-eol-update.html