master branch release , within which the development of new features continues (in a parallel supported stable only changes related to the elimination of serious errors and vulnerabilities are made.
Version 1.15.12 fixed a segmentation fault in the workflow that could occur if variables were used in the ssl_certificate or ssl_certificate_key directives and the mechanism was enabled The used to check the revocation of certificates. A week ago, nginx 1.15.1 was also released, in which the implementation of the ssl_stapling_file directive was changed to open a file in binary mode on Windows systems.
Additionally, the first release of the nginx 1.16 stable branch is expected soon, within which only changes related to the elimination of serious bugs and vulnerabilities will be made. The nginx 1.15 upstream branch will be replaced by the nginx 1.17 branch, which is scheduled to develop protocol support .
Source: opennet.ru