# Django 1.11.dev20170112000130 documentation

# Django 1.5.8 release notes

May 14, 2014

Django 1.5.8 fixes two security issues in 1.5.8.

## Caches may incorrectly be allowed to store and serve private data

In certain situations, Django may allow caches to store private data related to a particular session and then serve that data to requests with a different session, or no session at all. This can lead to information disclosure and can be a vector for cache poisoning.

When using Django sessions, Django will set a `Vary: Cookie` header to ensure caches do not serve cached data to requests from other sessions. However, older versions of Internet Explorer (most likely only Internet Explorer 6, and Internet Explorer 7 if run on Windows XP or Windows Server 2003) are unable to handle the `Vary` header in combination with many content types. Therefore, Django would remove the header if the request was made by Internet Explorer.

To remedy this, the special behavior for these older Internet Explorer versions has been removed, and the `Vary` header is no longer stripped from the response. In addition, modifications to the `Cache-Control` header for all Internet Explorer requests with a `Content-Disposition` header have also been removed as they were found to have similar issues.

## Malformed redirect URLs from user input not correctly validated

The validation for redirects did not correctly validate some malformed URLs, which are accepted by some browsers. This allows a user to be redirected to an unsafe URL unexpectedly.

Django relies on user input in some cases (e.g. `django.contrib.auth.views.login()`, `django.contrib.comments`, and i18n) to redirect the user to an “on success” URL. The security checks for these redirects (namely `django.utils.http.is_safe_url()`) did not correctly validate some malformed URLs, such as http:\\\djangoproject.com, which are accepted by some browsers with more liberal URL parsing.

To remedy this, the validation in `is_safe_url()` has been tightened to be able to handle and correctly validate these malformed URLs.