CVE-2026-54625: django CMS Page Cache Ignores Plugin-declared Vary Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-fwjf-m4qw-9f2x",
  "modified" : "2026-08-24T20:09:52Z",
  "published" : "2026-08-24T20:09:51Z",
  "aliases" : [ "CVE-2026-54625" ],
  "summary" : "django CMS: Page cache ignores plugin-declared Vary headers (disclosure & poisoning)",
  "details" : "### Summary\nThe CMS page cache key ignores the request headers that plugins declare via `get_vary_cache_on()`. The header is added to the response `Vary` header, but the CMS's own cache key does not incorporate the header values, so the first visitor's variant is served to all subsequent visitors regardless of their header values.\n\n### Details\n`_page_cache_key` (in `cms/cache/page.py`) keys only on cache prefix, site, language, path and timezone. `set_page_cache` collects the plugin-declared vary headers and calls `patch_vary_headers(response, ...)` (affecting only the emitted `Vary` header), but stores and retrieves the cached page under the header-agnostic key. `get_page_cache` therefore returns whichever variant was cached first.\n\n### Impact\n- **Information disclosure:** when a plugin varies its output on a request  header (e.g. `Country-Code`), the variant rendered for the first anonymous visitor is served to everyone until the entry expires, leaking request-specific content across users.\n- **Cache poisoning:** an unauthenticated attacker can prime the anonymous page cache with content rendered from attacker-chosen header values, which is then served to subsequent visitors.\n\nApplies only when `CMS_PAGE_CACHE` is enabled and at least one plugin implements `get_vary_cache_on()`.\n\n### Patches\nFixed in 5.0.8: the page cache now folds the request's values implements `get_vary_cache_on()`.\n\n### Patches\nFixed in 5.0.8: the page cache now folds the request's values for plugin-declared vary headers into the content key. The set of vary headers is persisted on write and looked up first on read (mirroring Django's  `learn_cache_key`/`get_cache_key`); a missing header-list entry degrades to a cache miss, never a wrong-variant hit.\n\n### Workarounds\nDisable `CMS_PAGE_CACHE`, or avoid plugins that rely on `get_vary_cache_on()`, until upgraded.\n\n### Credits\nReported by the security team at the University of Sydney ([@reporter]).",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "django-cms"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "5.0.8"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/django-cms/django-cms/security/advisories/GHSA-fwjf-m4qw-9f2x"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-54625"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/django-cms/django-cms/pull/8646"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/django-cms/django-cms/pull/8647"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/django-cms/django-cms/commit/8758714b865ffa79c6bcd0e5c503958ea48885aa"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/django-cms/django-cms/commit/d5dc1efa18d157445491c4b12c2dd1efd56f439f"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/django-cms/django-cms"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/django-cms/django-cms/releases/tag/5.0.8"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/django-cms/django-cms/releases/tag/5.1.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-349", "CWE-524" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-08-24T20:09:51Z",
    "nvd_published_at" : "2026-08-20T18:16:28Z"
  }
}