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Stored XSS

Stored XSS Guestbook

Scenario

VisitorLog's guestbook saves comments and renders them for every later reader. HTML you submit persists in the database. Leave a note that executes JavaScript when anyone views the page.

Your approach

  1. Post a harmless comment to see how entries display.
  2. Submit a persistent HTML payload with an automatic event handler.
  3. Reload the guestbook and confirm your script runs on view.
  4. Copy the flag from the lab success banner.
  5. Submit the stored payload flag.
Comments are stored and rendered with no encoding. Leave a payload, then reload — when it persists and executes, the flag appears.

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