HTTP Strict Transport Security (HSTS) header set to less than six months

OWASP 2013-A5 OWASP 2017-A6 OWASP 2021-A5 OWASP 2019-API7 OWASP PC-C1 CWE-16 ISO27001-A.14.1.2 WASC-15 WSTG-CONF-07

The HTTP Strict-Transport-Security response header is a header used in a website to notify a browser that it should only be accessed using HTTPS, instead of using HTTP. HTTP Strict Transport Security (HSTS) header’s max-age value is lower than the recommended value. It is only set to six months. The Strict-Transport-Security header is ignored by the browser when the website is accessed using HTTP. The browser does this because an attacker may intercept HTTP connections and inject the header or remove it. If the website is accessed over HTTPS and if the website doesn’t have any certificate errors, the browser knows your site is HTTPS capable and will use the Strict-Transport-Security header.


        Strict-Transport-Security: max-age=31536000; includeSubDomains



The main impact under this vulnerability:-

  • As the header is expired, the communication will continue in HTTP. The HTTP protocol is vulnerable to attacks like Man in the middle attack (MITM).

Mitigation / Precaution

  • sset max-age to a big value like 31536000 (12 months) or 63072000 (24 months)
        Strict-Transport-Security: max-age=31536000; includeSubDomains; preload


Related Articles