Low [CVE-2026-48588] Information disclosure due to improper caching of Set-Cookie responses

An issue was discovered in Django 6.0 before 6.0.7 and 5.2 before 5.2.16. `UpdateCacheMiddleware` and the `cache_page()` decorator cache responses that vary on cookies when the incoming request carries unrelated cookies, which allows remote attackers to read private data from the shared cache.

Earlier, unsupported Django series (such as 5.0.x, 4.1.x, and 3.2.x) were not evaluated and may also be affected. Django would like to thank Chris Whyland for reporting this issue.

When django.middleware.cache. UpdateCacheMiddleware or django.views.decorators.cache.cache_page is in use, responses that set a cookie are not excluded from caching if the request includes any cookie, even when that cookie is unrelated to the response (for example, a language or theme preference).

A remote attacker can retrieve a cached response intended for another user and obtain sensitive cookie data from the stored Set-Cookie header. This flaw is rated as Low impact.

When Django's UpdateCacheMiddleware or cache_page decorator is configured, responses containing sensitive Set-Cookie headers may be improperly cached and subsequently disclosed to other users if the initial request included any cookie.

This issue primarily affects Red Hat products utilizing Django with specific caching configurations, potentially leading to limited information exposure.