This article is a part of our Vulnerability Database (back to index)
Cross-site Scripting occurrences in Wire Server
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). (2021-09-30, CVE-2021-41101)
Why Cross-site Scripting can be dangerous
Cross site scripting is an attack where a web page executes code that is injected by an adversary. It usually appears, when users input is presented. This attack can be used to impersonate a user, take over control of the session, or even steal API keys.
The attack can be executed e.g. when you application injects the request parameter directly into the HTML code of the page returned to the user:
https://server.com/confirmation?message=Transaction+Complete
what results in:
<span>Confirmation: Transaction Complete</span>
In that case the message can be modified to become a valid Javascript code, e.g.:
https://server.com/confirmation?message=<script>dangerous javascript code here</script>
and it will be executed locally by the user's browser with full access to the user's personal application/browser data:
<span>Confirmation: <script>dangerous javascript code here</script></span>