I bet you’re here because you’ve run into the puzzling Django error
CSRF verification failed. Request aborted. Reason given for failure: Referer checking failed - http://<domain>/ does not match https://<domain>/.
I’ll double down that this happens when you try to make your login form post to HTTPS,
If I’m mostly right, you’ve run into the problem I’ve solved. If I’m not right and you somehow ended up on this page, I’d love to hear about it.
In the CSRF middleware, Django does an extra check when a request comes over HTTPS to ensure it comes from the same site (same origin check).
If any portion of your site benefits from HTTPS, you probably should run your entire site over HTTPS. You can use django-sslify to force your website to operate in HTTPS mode all the time.
Furthermore, if you want to disable CSRF checking for your own views, there are other methods
you can use, for example the
However, if the views are not under your control and you are comfortable n trading some security for not really that much convenience, you can use django-permissivecsrf to work around this error.
Use the instructions in the README file on GitHub or on PyPI to get this project up an running.
Mostly it consists of installing django-permissivecsrf and adding
The gist of why this happens is explained in point #4 of the How it works section of the Django documentation on Cross Site Request Forgery (emphasis mine):
4) In addition, for HTTPS requests, strict referer checking is done by CsrfViewMiddleware. This is necessary to address a Man-In-The-Middle attack that is possible under HTTPS when using a session independent nonce, due to the fact that HTTP ‘Set-Cookie’ headers are (unfortunately) accepted by clients that are talking to a site under HTTPS. (Referer checking is not done for HTTP requests because the presence of the Referer header is not reliable enough under HTTP.)
In other words, because the HTTPS headers are encrypted, the HTTP-Referer header is resilient against MITM attacks, so it can be safely used to check and make sure the CSRF cookie is originated by the same site that served the page and that the referring page has also been served over HTTPS, which means that page has also been protected against header injections.
The same check could be made on HTTP calls as well, but since HTTP headers are not encrypted, they could be easily faked and thus the check would be a useless placebo.
This explanation is also present, in comment form, in this f92a21daa7 commit by spookylukey aka Luke Plant, and further detailed by him in a reply to a complaint about the strictness of CSRF Referer check on the django-developers maillist.
How django-permissivecsrf works
The Django CSRF middleware performs an extra-check if the request is over HTTPS to ensure that the request came from the same site, i.e. that the referrer (HTTP-Referer header) matches the current site, and that the schema of the referrer is also HTTPS.
In other words, in ensures that the call to https://example.com/account/login
came from another page of https://example.com/. As such, if you put your login
form on your non-secure homepage, http://example.com/, but use a secure target
for your form’s action attribute,
<form action="https://example.com/account/login" method="POST">,
Django’s check will fail because::
'http://example.com/' != ('https://%s/' % request.get_host())
However, Django will not perform the CSRF check at all if the
request object has
_dont_enforce_csrf_checks set to True. That’s what PermissiveCSRF relies on:
if the request came from the same site, regardless the schema, it sets
to True, thus telling the Django CSRF middleware to skip the CSRF check for that request.
This only happens if:
DEBUG == True. Your production server should always be HTTPS;
HTTP-Refererheader is present;
- The request is for an HTTPS URL (i.e.
request.is_secure() == True);
- and the referrer uses HTTP.
In all other cases it defers to Django for normal processing.
There’s only one thing to take away from all this: in production use HTTPS (see django-sslify). Period.