This document explains all middleware components that come with Django. For information on how to use them and how to write your own middleware, see the middleware usage guide.
Adds a few conveniences for perfectionists:
Forbids access to user agents in the
DISALLOWED_USER_AGENTSsetting, which should be a list of compiled regular expression objects.
Trueand the initial URL doesn’t end with a slash, and it is not found in the URLconf, then a new URL is formed by appending a slash at the end. If this new URL is found in the URLconf, then Django redirects the request to this new URL. Otherwise, the initial URL is processed as usual.
foo.com/barwill be redirected to
foo.com/bar/if you don’t have a valid URL pattern for
foo.com/barbut do have a valid pattern for
True, URLs that lack a leading “www.” will be redirected to the same URL with a leading “www.”
Both of these options are meant to normalize URLs. The philosophy is that each URL should exist in one, and only one, place. Technically a URL
foo.com/baris distinct from
foo.com/bar/– a search-engine indexer would treat them as separate URLs – so it’s best practice to normalize URLs.
Handles ETags based on the
USE_ETAGSis set to
True, Django will calculate an ETag for each request by MD5-hashing the page content, and it’ll take care of sending
Not Modifiedresponses, if appropriate.
CommonMiddleware and override the attribute to customize the redirects
issued by the middleware.
Security researchers recently revealed that when compression techniques
GZipMiddleware) are used on a website, the site becomes
exposed to a number of possible attacks. These approaches can be used to
compromise, among other things, Django’s CSRF protection. Before using
GZipMiddleware on your site, you should consider very carefully whether
you are subject to these attacks. If you’re in any doubt about whether
you’re affected, you should avoid using
GZipMiddleware. For more
details, see the the BREACH paper (PDF) and breachattack.com.
Compresses content for browsers that understand GZip compression (all modern browsers).
This middleware should be placed before any other middleware that need to read or write the response body so that compression happens afterward.
It will NOT compress content if any of the following are true:
- The content body is less than 200 bytes long.
- The response has already set the
- The request (the browser) hasn’t sent an
You can apply GZip compression to individual views using the
Conditional GET middleware¶
Handles conditional GET operations. If the response has a
Last-Modified header, and the request has
If-Modified-Since, the response is replaced by an
Also sets the
Enables language selection based on data from the request. It customizes content for each user. See the internationalization documentation.
LocaleMiddleware and override the attribute to customize the redirects
issued by the middleware.
Enables cookie- and session-based message support. See the messages documentation.
If your deployment situation allows, it’s usually a good idea to have your
front-end Web server perform the functionality provided by the
SecurityMiddleware. That way, if there are requests that aren’t served
by Django (such as static media or user-uploaded files), they will have
the same protections as requests to your Django application.
django.middleware.security.SecurityMiddleware provides several security
enhancements to the request/response cycle. Each one can be independently
enabled or disabled with a setting.
HTTP Strict Transport Security¶
For sites that should only be accessed over HTTPS, you can instruct modern browsers to refuse to connect to your domain name via an insecure connection (for a given period of time) by setting the “Strict-Transport-Security” header. This reduces your exposure to some SSL-stripping man-in-the-middle (MITM) attacks.
SecurityMiddleware will set this header for you on all HTTPS responses if
you set the
SECURE_HSTS_SECONDS setting to a non-zero integer value.
When enabling HSTS, it’s a good idea to first use a small value for testing,
SECURE_HSTS_SECONDS = 3600 for one
hour. Each time a Web browser sees the HSTS header from your site, it will
refuse to communicate non-securely (using HTTP) with your domain for the given
period of time. Once you confirm that all assets are served securely on your
site (i.e. HSTS didn’t break anything), it’s a good idea to increase this value
so that infrequent visitors will be protected (31536000 seconds, i.e. 1 year,
Additionally, if you set the
SecurityMiddleware will add the
includeSubDomains tag to
Strict-Transport-Security header. This is recommended (assuming all
subdomains are served exclusively using HTTPS), otherwise your site may still
be vulnerable via an insecure connection to a subdomain.
The HSTS policy applies to your entire domain, not just the URL of the response that you set the header on. Therefore, you should only use it if your entire domain is served via HTTPS only.
Browsers properly respecting the HSTS header will refuse to allow users to bypass warnings and connect to a site with an expired, self-signed, or otherwise invalid SSL certificate. If you use HSTS, make sure your certificates are in good shape and stay that way!
If you are deployed behind a load-balancer or reverse-proxy server, and the
Strict-Transport-Security header is not being added to your responses,
it may be because Django doesn’t realize that it’s on a secure connection;
you may need to set the
Some browsers will try to guess the content types of the assets that they
fetch, overriding the
Content-Type header. While this can help display
sites with improperly configured servers, it can also pose a security
To learn more about this header and how the browser treats it, you can read about it on the IE Security Blog.
To prevent the browser from guessing the content type and force it to
always use the type provided in the
Content-Type header, you can pass
X-Content-Type-Options: nosniff header.
do this for all responses if the
Note that in most deployment situations where Django isn’t involved in serving
user-uploaded files, this setting won’t help you. For example, if your
MEDIA_URL is served directly by your front-end Web server (nginx,
Apache, etc.) then you’d want to set this header there. On the other hand, if
you are using Django to do something like require authorization in order to
download files and you cannot set the header using your Web server, this
setting will be useful.
X-XSS-Protection: 1; mode=block¶
The X-XSS-Protection header is used to control the operation of the XSS filter.
To enable the XSS filter in the browser, and force it to always block
suspected XSS attacks, you can pass the
X-XSS-Protection: 1; mode=block
SecurityMiddleware will do this for all responses if the
SECURE_BROWSER_XSS_FILTER setting is
The browser XSS filter is a useful defense measure, but must not be relied upon exclusively. It cannot detect all XSS attacks and not all browsers support the header. Ensure you are still validating and sanitizing all input to prevent XSS attacks.
If your site offers both HTTP and HTTPS connections, most users will end up with an unsecured connection by default. For best security, you should redirect all HTTP connections to HTTPS.
If you set the
SECURE_SSL_REDIRECT setting to True,
SecurityMiddleware will permanently (HTTP 301) redirect all HTTP
connections to HTTPS.
For performance reasons, it’s preferable to do these redirects outside of
Django, in a front-end load balancer or reverse-proxy server such as
SECURE_SSL_REDIRECT is intended for the deployment
situations where this isn’t an option.
SECURE_SSL_HOST setting has a value, all redirects will be
sent to that host instead of the originally-requested host.
If there are a few pages on your site that should be available over HTTP, and
not redirected to HTTPS, you can list regular expressions to match those URLs
If you are deployed behind a load-balancer or reverse-proxy server and
Django can’t seem to tell when a request actually is already secure, you
may need to set the
Enables session support. See the session documentation.
site attribute representing the current site to every incoming
HttpRequest object. See the sites documentation.
user attribute, representing the currently-logged-in user, to
HttpRequest object. See Authentication in Web requests.
Middleware for utilizing Web server provided authentication. See Authentication using REMOTE_USER for usage details.
Middleware for utilizing Web server provided authentication when enabled only on the login page. See Using REMOTE_USER on login pages only for usage details.
CSRF protection middleware¶
Adds protection against Cross Site Request Forgeries by adding hidden form fields to POST forms and checking requests for the correct value. See the Cross Site Request Forgery protection documentation.
Here are some hints about the ordering of various Django middleware classes:
It should go near the top of the list if you’re going to turn on the SSL redirect as that avoids running through a bunch of other unnecessary middleware.
Before those that modify the
Before any middleware that may change or use the response body.
CommonMiddleware: uses its
One of the topmost, after
SessionMiddleware(uses session data) and
Before any middleware that may change the response (it calculates
GZipMiddlewareso it won’t calculate an
ETagheader on gzipped contents.
Before any view middleware that assumes that CSRF attacks have been dealt with.
SessionMiddleware: uses session storage.
SessionMiddleware: can use session-based storage.
After any middleware that modifies the
Varyheader: that header is used to pick a value for the cache hash-key.
Should be near the bottom as it’s a last-resort type of middleware.
Should be near the bottom as it’s a last-resort type of middleware.