Web message manipulation
Summary: PortSwigger Research describes web message manipulation vulnerabilities, which arise when a script sends attacker-controllable data as a web message to another document in the browser. An attacker can construct a page that, when visited by a user, causes the browser to send a web message containing data under the attacker's control, and the postMessage() method can lead to vulnerabilities if the receiving event listener handles incoming data unsafely.
Why it matters: The guidance centers on verifying the origin of incoming messages and explicitly specifying the target window for cross-origin messages - controls that, if missing, let an attacker-supplied page feed data straight into your application's message handler.
Read the original at PortSwigger Research ↗
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- Vulnerabilities & Patching
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