= security scan =
https://securityheaders.com/?q=https%3A%2F%2Fmathux.org&followRedirects=on

= fix =
https://www.justegeek.fr/mettre-en-place-len-tete-referrer-policy-pour-securiser-son-site/
https://scotthelme.co.uk/a-new-security-header-referrer-policy/