Ajax request header manipulation (reflected DOM-based)
Summary: Reflected DOM-based vulnerabilities occur when data from a request is echoed into the immediate response inside a part of the DOM that a client-side script then processes unsafely. Ajax request header manipulation is a specific case where a script writes controllable data into a header of an XmlHttpRequest, letting an attacker construct a URL that, when visited by another user, sets an arbitrary header in the subsequent Ajax request.
Why it matters: The impact depends entirely on what the server does with that header: if it controls the behavior of the Ajax request, an attacker can make the user perform unintended actions, which is why PortSwigger advises never setting Ajax headers from untrusted data for anything tied to privileged actions.
Read the original at PortSwigger Research ↗
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