Django 1.11.15 release notes
August 1, 2018
Django 1.11.15 fixes a security issue in 1.11.14.
CVE-2018-14574: Open redirect possibility in CommonMiddleware
If the CommonMiddleware and the APPEND_SLASH setting are both enabled, and if the project has a URL pattern that accepts any path ending in a slash (many content management systems have such a pattern), then a request to a maliciously crafted URL of that site could lead to a redirect to another site, enabling phishing and other attacks.
CommonMiddleware
now escapes leading slashes to prevent redirects to other domains.