Codfront Labs » Http Strict Transport Security : Security Vulnerabilities, CVEs,

The HTTP Strict Transport Security (HSTS) module 6.x-1.x before 6.x-1.1 and 7.x-1.x before 7.x-1.2 for Drupal does not properly implement the "include subdomains" directive, which causes the HSTS policy to not be applied to subdomains and allows man-in-the-middle attackers to have unspecified impact via unknown vectors.