Discover how attackers abuse clipboard paste handling to trigger Blind XSS from setup to exploitation
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Cross-Site Scripting (XSS) vulnerabilities are among the most common yet dangerous issues in web applications. While many developers are aware of stored, reflected, or DOM-based XSS, there are lesser-known variants can still catch even experienced developers by surprise. One such variant is Clipboard Paste XSS. This attack abuses how web applications handle content pasted from a user’s clipboard.
In this article, we’ll break down the attack step by step, demonstrate it with a proof-of-concept (PoC) and share practical techniques for detection and prevention.
Clipboard Paste XSS occurs when a web application:
- Accepts HTML content from the clipboard during a paste event
- Inserts that HTML directly into the DOM (e.g., using innerHTML).
- Fails to sanitize or properly escape the pasted content.
This creates a situation where a malicious payload copied into the clipboard by an attacker can execute JavaScript once pasted…