CORS `Access-Control-Allow-Origin` settings are too lenient

CVE-2021-41101

What is CVE-2021-41101?

wire-server is an open-source back end for Wire, a secure collaboration platform. Before version 2.106.0, the CORS Access-Control-Allow-Origin header set by nginz is set for all subdomains of .wire.com (including wire.com). This means that if somebody were to find an XSS vector in any of the subdomains, they could use it to talk to the Wire API using the user's Cookie. A patch does not exist, but a workaround does. To make sure that a compromise of one subdomain does not yield access to the cookie of another, one may limit the Access-Control-Allow-Origin header to apps that actually require the cookie (account-pages, team-settings and the webapp).

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