This article is a part of our Vulnerability Database (back to index)
Cross-site Scripting occurrences in Netlify-ipx
netlify-ipx is an on-Demand image optimization for Netlify using ipx. In versions prior to 1.2.3, an attacker can bypass the source image domain allowlist by sending specially crafted headers, causing the handler to load and return arbitrary images. Because the response is cached globally, this image will then be served to visitors without requiring those headers to be set. XSS can be achieved by requesting a malicious SVG with embedded scripts, which would then be served from the site domain. Note that this does not apply to images loaded in `` tags, as scripts do not execute in this context. The image URL can be set in the header independently of the request URL, meaning any site images that have not previously been cached can have their cache poisoned. This problem has been fixed in version 1.2.3. As a workaround, cached content can be cleared by re-deploying the site. (2022-09-23, CVE-2022-39239)
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>