#29802: Allow skipping CSRF check for Referer header
-------------------------------------+-------------------------------------
Reporter: Aaron1011 | Owner: nobody
Type: New feature | Status: new
Component: CSRF | Version: 2.1
Severity: Normal | Resolution:
Keywords: | Triage Stage:
csrf,https,hsts,referer | Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Description changed by Aaron1011:
Old description:
> Currently, Django's CSRF middleware will reject any 'non-safe' HTTPS
> request that lacks a Referer header:
> https://github.com/django/django/blob/22e8ab02863819093832de9f771bf40a62a6bd4a/django/middleware/csrf.py#L242
>
> However, some users may prevent their browsers from sending the Referer
> header, due to privacy concerns. These users are unable to submit 'non-
> safe' requests (e.g. POST requests) on HTTPS-enabled Django-powered
> website that uses CSRF protection.
>
> For some websites, checking the Referer header may provide no added
> security benefit. For example, an HSTS-preloaded website which controls
> all of its subdomains has nothing to gain from this check - there are no
> untrusted subdomains which can mount an attack, and HSTS prevents an HTTP
> MITM attack.
>
> To allow these websites to provide more flexibility to their users,
> Django should support disabling this CSRF Referer check. This could be
> done through a new setting, e.g. ' CSRF_REFERER_CHECK' (defaulting to
> 'True' to avoid breaking existing sites).
New description:
Currently, Django's CSRF middleware will reject any 'non-safe' HTTPS
request that lacks a Referer header:
https://github.com/django/django/blob/22e8ab02863819093832de9f771bf40a62a6bd4a/django/middleware/csrf.py#L242
However, some users may prevent their browsers from sending the Referer
header, due to privacy concerns. These users are unable to submit 'non-
safe' requests (e.g. POST requests) on HTTPS-enabled Django-powered
website that use CSRF protection.
For some websites, checking the Referer header may provide no added
security benefit. For example, an HSTS-preloaded website which controls
all of its subdomains has nothing to gain from this check - there are no
untrusted subdomains which can mount an attack, and HSTS prevents an HTTP
MITM attack.
To allow these websites to provide more flexibility to their users, Django
should support disabling this CSRF Referer check. This could be done
through a new setting, e.g. ' CSRF_REFERER_CHECK' (defaulting to 'True' to
avoid breaking existing sites).
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Ticket URL: <https://code.djangoproject.com/ticket/29802#comment:1>
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