Doubled Character XSS Manipulations

Attackers exploit this weakness by submitting input where key characters in a script payload are doubled, such as turning `<script>` into `<sscriptcript>`. Many basic security filters perform a single pass to remove or escape dangerous strings like `script`. When the filter removes the expected sequence, the remaining characters collapse back into a valid, executable script tag, effectively bypassing the protection. To prevent this, developers must implement robust, context-aware output encoding and validation that doesn't rely solely on simple string replacement. Input sanitization should be performed after decoding and before rendering, using well-tested libraries designed to neutralize such obfuscation techniques. This ensures the user input is treated as plain text data, not executable code, regardless of character manipulation attempts.