GHSA-FWJF-M4QW-9F2X django CMS: Page cache ignores plugin-declared Vary headers (disclosure & poisoning)

Summary The CMS page cache key ignores the request headers that plugins declare via getvarycacheon. 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 o...