March 18, 2015
Django 1.4.20 fixes one security issue in 1.4.19.
Django relies on user input in some cases (e.g.
django.contrib.auth.views.login() and i18n)
to redirect the user to an “on success” URL. The security checks for these
redirects (namely django.utils.http.is_safe_url()) accepted URLs with
leading control characters and so considered URLs like \x08javascript:...
safe. This issue doesn’t affect Django currently, since we only put this URL
into the Location response header and browsers seem to ignore JavaScript
there. Browsers we tested also treat URLs prefixed with control characters such
as %08//example.com as relative paths so redirection to an unsafe target
isn’t a problem either.
However, if a developer relies on is_safe_url() to
provide safe redirect targets and puts such a URL into a link, they could
suffer from an XSS attack as some browsers such as Google Chrome ignore control
characters at the start of a URL in an anchor href.
May 26, 2021