Round 1 fixed the address pre-emption chain by letting a later registration replace the password on
an unverified account and delete its outstanding verify tokens. Round 2 read that code and showed it
was worse than what it fixed, so it goes back out.
It closes nothing. The rule is symmetric and an attacker can simply register last — on a timer,
inside the five-per-five-minutes budget — while the owner registers once. What it does add is two
primitives an unauthenticated caller did not have: overwrite a real registrant's chosen password,
and delete the confirmation link already sitting in their inbox (the approval mail's 7-day token is
an ordinary verify token, so the blanket delete took that too). Worst of all it fired on the rows
SEC-10 left stripped — password_hash NULL, password_revoked_at set, active — installing an
attacker's password where the entire state means "there is none", and clearing the stamp that is the
only reason password-reset still accepts them. That is a straight takeover which did not exist
before, in the code written to prevent one.
The owner's recourse needed no new primitive and already worked: password-reset accepts a
pre-empted account, proves the mailbox, rewrites the hash and bumps the session epoch. What remains
is the bounded window between a confirmation click and that reset, which is SEC-16 — logged with
this attempt written down, so the next person does not reach for it again.
Two smaller round-2 findings go with it. `upsert_pending_invite`'s new exact-spelling tie-break ran
before any status preference, so it could deterministically pick a DENIED sibling over a pending one
and reopen it — the very outcome its comment claimed to prevent; the status preference now comes
first. And `send_invitation` activated the account before the send it might have to report as
failed, so a request the UI called a failure had quietly let someone in; activation now follows a
mail that actually left. The verify token minted to render that mail still commits either way — it
is single-use, expires on its own and was mailed nowhere, and the note says so rather than leaving
the next reader to wonder whether it was missed.
peter
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