Fiber is an Express inspired web framework written in Go. Prior to 3.4.0, the helmet middleware in middleware/helmet/helmet.go never sets the Strict-Transport-Security response header even when HSTSMaxAge is configured because it checks c.Protocol() for https instead of c.Scheme(). This issue is fixed in version 3.4.0.
https://github.com/gofiber/fiber/security/advisories/GHSA-gv83-gqw6-9j2c
https://github.com/gofiber/fiber/releases/tag/v3.4.0
https://github.com/gofiber/fiber/pull/4389
https://github.com/gofiber/fiber/commit/04dd4e7754f61768fddccacc79057e416f13e6bf