Pirate Chain: A Bug Printed 39.8M ARRR, and the Coins Vanished Into the Privacy Pool

In the early hours of 15 October 2026, the people who run Pirate Chain told everyone holding its coin to stop. Do not send ARRR. Do not receive it. Exchanges were asked to shut their doors to it. An exploit had been found, the team wrote on X, "in the new transparent layer related to the Ironwood turnstile for supply accounting", and the plan was to wind the whole blockchain back to 20:00 universal time the previous day, as if the hours since had never happened.

By the afternoon that plan was gone. The scale of the problem had become clearer: someone had created about 39.8 million ARRR out of thin air, roughly 20 percent on top of the 196.2 million coins already in circulation. At the price on the day, between $0.27 and $0.28, that was about $10.7 million of new money that nobody had earned.

©CMZ chart. Data: CoinGecko, Pirate Chain

The new coins went straight into the one place on Pirate Chain where nobody can see anything. The project said itself that their full movement after that "cannot be traced".

A coin built to be invisible

Pirate Chain launched in 2018 and is a privacy coin. Most blockchains, Bitcoin included, work like a public bank statement: anyone can see which account paid which, and how much. A privacy coin works more like cash. The payment happens, but outsiders cannot see who paid whom or how much.

Pirate Chain takes this further than most. It is built on code that started life as Zcash, the best-known privacy coin, but where Zcash lets users choose between public and private transactions, Pirate Chain makes every payment private. It uses zk-SNARKs, a kind of mathematical proof that lets the network confirm a payment is valid, with enough money behind it, without ever seeing the amount or the names. Private balances sit in what are called shielded pools. For years the main one has been Sapling, a design also borrowed from Zcash.

That privacy has a cost, and this week showed it. On a public chain, if extra coins appear, anyone can add up the balances and spot that the total is wrong. In a shielded pool, the balances are hidden by design, so the usual check is impossible. The total supply is something everyone has to trust the code to enforce.

The upgrade that was meant to fix that

On 3 October 2026, at 19:00 universal time, Pirate Chain switched on an upgrade called Ironwood. It was a hard fork, a compulsory software change that every computer on the network had to accept, the way a stock exchange might move every broker onto a new trading system on the same morning. Users of the Treasure Chest wallet and the command-line wallet had to move to version 6.0.7 or later.

Ironwood had its own back story. In May 2026 a researcher named Taylor Hornby, working for Shielded Labs, found a serious flaw in Orchard, Zcash's newest private pool, one that could in principle have let someone forge coins. Zcash moved users to a new pool called Ironwood, which went live on 28 July, and restricted Orchard so money could only leave it. Pirate Chain had never adopted Orchard and said at the time it was unaffected. With Ironwood it skipped Orchard altogether and jumped straight from Sapling to the new design, which uses a proof system called Halo 2 and was checked with computer-verified mathematics.

Ironwood also brought a "turnstile". This is an accounting rule. Because nobody can see inside a private pool, the network keeps a public tally of how much value goes in and how much comes out, and refuses any withdrawal that would take out more than was ever put in. It works like a ticket counter at a stadium gate: nobody needs to know who is inside, only that the number leaving can never exceed the number who entered. On Pirate Chain this check runs in a public, see-through layer that sits beside the private pool.

That layer is where the hole was. The turnstile was meant to make inflation easy to spot. Eleven days after it went live, it became the way in.

Two checks that failed together

Pirate Chain has not yet published its full technical report, but its statement of 15 October, posted on X at 16:46 universal time, described two failures that combined.

The first was a bypassed issuance check. Every blockchain has a rule about when new coins may be created, usually only as a reward to whoever adds the next block, on a fixed schedule. That rule was sidestepped.

The second was that the network misread output scripts. An output script is the small instruction attached to every payment saying where the money goes and what is needed to spend it, like the payee line and signature box on a cheque. The software read some of those instructions wrongly.

Put together, the two let someone create coins outside the schedule and have the network accept them as real. The project said it found no evidence that its notary keys, which help secure the chain, or the private-transaction cryptography itself had been broken. The maths held. The bookkeeping beside it did not.

Where the coins went

As soon as the 39.8 million ARRR existed, they were moved into the Sapling shielded pool. From there they are cash in a crowd. The project said only that the activity it could see appeared to be mostly limited to transactions on the chain itself.

At least one attempt to cash out was caught. NonKYC, a small exchange that does not ask customers for identity documents, flagged suspicious ARRR deposits linked to the exploit, restricted the account involved and blocked its withdrawals. MEXC, a much larger exchange, suspended ARRR deposits and withdrawals at the project's request, according to its maintenance notices. Pirate Chain's choice of trading venues was already narrow: TradeOgre, a privacy-friendly exchange that was one of its main markets, was shut down by Canadian police in 2025, and the project has said it does not want to compromise its privacy to win listings on big regulated platforms.

How much, if any, of the $10.7 million was turned into real money is not known. Whoever did this may still hold most of it.

The rollback that could not happen

The first answer, posted at about 02:20 universal time on 15 October, was a rollback: return the chain to its state at 1:00pm Pacific time (20:00 universal time) on 14 October and throw away every block made after that. It is the equivalent of a bank cancelling a whole day of transactions, the fraudulent ones and the honest ones alike.

A bank can do that alone. A blockchain cannot. Rolling back means persuading the miners who add blocks, the exchanges that credit deposits and the people running the network's computers to agree on the same older version of history at the same time. Ravencoin did it in August, and its own developers could not stop the mining pools picking an earlier date than they wanted.

Pirate Chain's follow-up conceded the point. Because the network is decentralised, the team said, it is "not possible to freeze the network or unilaterally rollback its blockchain history". The chain kept running. The operators of its delayed Proof of Work system, a backup that copies Pirate Chain's history onto Komodo and then Litecoin to make it harder to rewrite, voluntarily paused, which itself leaves the chain less protected for now. Exchanges and mining pools were asked to stop. Holders were asked, again, not to move funds while a recovery plan is drawn up.

The market barely flinched. ARRR traded at about $0.26 on 16 October, down between 4 and 6.5 percent on the day according to CoinGecko snapshots, with only about $485,000 traded in 24 hours. Price sites still listed a 200 million total supply, the cap written into Pirate Chain's code, which appears not to count the new coins at all. The coin was already more than 98 percent below its April 2021 peak.