Mercurial Plugin prior to 2.12, 2.10.1, 2.9.1, and 2.8.1 does not perform a permission check in an HTTP endpoint.
This allows attackers with Overall/Read permission to obtain a list of names of configured Mercurial installations.
Mercurial Plugin 2.12, 2.10.1, 2.9.1, and 2.8.1 performs permission checks when listing configured Mercurial installations.