Point release fixing a theft vector in FundsMover self-payment
rebalances (issue #322):
- The returning HTLC was settled by matching payment hash and payment
secret only, without checking the amount. The last-hop peer relays
our onion (and thus the secret) intact but chooses the offered
amount, so it could settle a reduced amount, learn the preimage, and
claim the full amount upstream. - The claim now requires the exact constructed amount before the
preimage is released; a mismatched HTLC fails and the funds return
upstream.
Upgrading is recommended.
See CHANGELOG.md for details.