Boost.Graph is a header-only C++ template library. Most issues that look like security problems are caused by misuse of the API, undefined behavior in caller code, or violating a documented precondition. Those should be filed as regular GitHub issues.
If you believe you have found a genuine vulnerability in the library itself, please report it privately through GitHub's private vulnerability reporting rather than opening a public issue.
Fixes land on the develop branch and ship with the next Boost release.
No back-porting to older releases is guaranteed.