Pirate Chain bug minted 39.8 million ARRR, and the coins vanished into the shielded pool

Pirate Chain (ARRR) says a bug in its transaction checks, discovered on 14 October 2026, let someone create about 39.8 million ARRR out of nothing and raise the coin’s supply by roughly 20%. The new coins went straight into the Sapling shielded pool, where nobody can follow them. The team gave those figures in an update posted on X at 16:46 UTC on 15 October, and in the same post it dropped the rollback it had promised some 14 hours earlier.

The exploit came eleven days after Ironwood, the project’s new shielded pool, went live on mainnet. Exchanges halted ARRR deposits and withdrawals after the team notified them, and the notaries that anchor Pirate Chain blocks to other chains paused their work. The chain itself keeps running.

ARRR traded at $0.2612 at about 08:20 UTC on 16 October, down 5.8% over 24 hours, according to CoinGecko. CoinMarketCap showed a lower $0.2352 at the same time, down 10.8%. That is a mild move for a coin whose supply just grew by a fifth. Our reading, explained below, is that closed exchange deposits explain more of it than investor confidence does.

Pirate Chain exploit: 39.8 million ARRR minted, then shielded

In its 15 October update, titled “Pirate Chain Import Exploit Update”, the team described the problem as a transaction validation vulnerability in its source code. It said the flaw was found on 14 October and allowed the “unauthorized creation of approximately 39.8 million ARRR, increasing the supply by approximately 20%”.

Two separate failures were needed. In the team’s words: “The exploit combined two validation failures bypassing the issuance check and incorrect interpretation of the output scripts.” The minted coins were moved at once into Sapling, the shielded pool that predates Ironwood. The team says the full path of the funds after that cannot be traced. On a privacy chain that is the design, not a failure.

One trail did surface. NonKYC, the exchange with the largest ARRR volume on CoinGecko, spotted suspicious deposits, restricted the account involved and blocked its withdrawals. The team did not say how many coins reached that account. Beyond that deposit, it believes the activity stayed mostly on-chain.

The project also tried to limit the damage to its reputation for privacy. “Evidence does not indicate any compromise of notary keys or the cryptography underlying Pirate Chain’s shielded transactions,” the update said. If that holds, the zero-knowledge proofs that hide balances did their job, and the hole sat in ordinary code that decides whether a transaction is allowed.

The rollback plan lasted about 14 hours

The first notice came at 02:20 UTC on 15 October. In it, the team said an exploit had been found “in the new transparent layer related to the Ironwood turnstile for supply accounting”. Its fix was blunt: “The developers will be rolling the chain back to 14 October 2026, 1:00 PM Pacific Time,” which is 20:00 UTC. Blocks mined after that point would have been discarded.

The same notice said “all exchanges have been notified” and were suspending deposits and withdrawals. Users were told not to send or receive funds and to stay away from their wallets. MEXC, one of the three main ARRR venues, suspended ARRR deposits and withdrawals at the project’s request, according to Crypto Times, which cited MEXC maintenance notices. Coindaro could not find MEXC’s notice itself.

By 16:46 UTC the plan was gone. “Because Pirate Chain is decentralized, it is not possible to freeze the network or unilaterally rollback its blockchain history,” the update said. A rollback only works if miners, node operators, mining pools and exchanges all switch to the shorter chain together. The developers cannot force that, and the longer the chain runs, the more honest transactions a rollback would erase.

What the team did instead: the operators of delayed proof of work (dPoW), the notary system inherited from Komodo that writes Pirate Chain checkpoints to Komodo and Litecoin, agreed to suspend notarizations for a while. Exchanges and mining pools were asked to pause on a voluntary basis while a recovery plan is drawn up “in collaboration with other communities”. Users are still asked not to move funds.

Two GitHub fixes match the flaws the team described

The team’s post gives no code references. On the project’s public GitHub, though, developer “Cryptoforge” pushed two fixes to the dev branch in the hours around the announcements, and they line up with the two failures the team named. Treat them as fixes that match the described flaw, not as the team’s confirmed explanation, which is promised for a post-mortem.

Forged coin imports skipped the proof-of-burn check

The first commit, at 23:50 UTC on 14 October, is titled “Require proof of burn for coin imports in ConnectBlock”. Pirate Chain inherits from Komodo a “coin import” feature: coins burned on one chain can be recreated on another, once the burn is proven. According to the commit, block validation skipped input and fee accounting for every transaction shaped like a mint. The test meant to catch the block reward (the coinbase) also caught import-shaped transactions, so those never reached the check that verifies the burn. Their outputs were accepted with no proof that anything had been burned.

The fix restores the old behaviour, under which imports are validated “as before v6.0.0”. That wording points to a regression introduced with the 6.0.0 release, the one that brought Ironwood. The commit adds tests in which blocks carrying forged imports are rejected. The team’s own title, “Import Exploit Update”, fits this reading.

A misread time-lock script got around the transparent-output rule

The second commit, at 16:09 UTC on 15 October, rejects “non-canonical” CLTV scripts so that output addresses cannot be spoofed. CLTV is a time-lock script type. A crafted output could be read as a CLTV script, and the parser then reported an address the script does not actually require. Pirate Chain only lets transparent outputs go to approved destinations, and this trick got around that restriction. It matches the “incorrect interpretation of the output scripts” in the team’s post.

Neither fix has shipped as a signed release. The dev branch was bumped to 6.0.10-beta2 at 04:47 UTC and 6.0.10-beta3 at 16:14 UTC on 15 October. When Coindaro checked GitHub at 08:35 UTC on 16 October, the latest stable release was still v6.0.9, published at 19:27 UTC on 13 October, the day before the exploit, and no commit had landed since beta3. The team had posted nothing on X after its 16:46 UTC update.

Why the Ironwood turnstile did not stop it

Version 6.0.0 came out on 17 August 2026 and introduced Ironwood, a new shielded pool built on Halo2 proofs and the Pallas curve. It began as an integration of Zcash’s Orchard protocol and grew into a separate pool. According to the 6.0.0 release notes, activation was set by timestamp rather than block height, for Saturday 3 October at 19:00 UTC. The changelog also lists the enforcement of “ZIP 209 turnstile checks” for the Sapling and Orchard pools.

ZIP 209 is a Zcash rule. Each shielded pool keeps a public running balance of what went in and what came out, and the chain rejects any block that would take more out of a pool than was ever put in. That catches counterfeiting inside the private pool, where balances are invisible.

It does nothing against coins forged outside the pool and then deposited into it. That is what happened here, if the GitHub fixes describe the attack: the 39.8 million ARRR were created on the transparent side, through forged imports, and only then shielded. To the turnstile they looked like a normal deposit.

What a 20% supply increase means in numbers

The project caps supply at 200 million ARRR, and trackers show 196.21 million in circulation. None of them has added the minted coins. Here is what the team’s figure does to those numbers. The calculations are Coindaro’s.

That last line is theory. With deposits frozen and 24-hour volume of $487,000 on CoinGecko, nobody could sell $10.4 million of ARRR anywhere near that price. Unless a recovery plan removes or quarantines the minted coins, ARRR would carry about 36 million coins more than its own cap.

Why the Pirate Chain price fell only 6% to 11%

The market reaction has been small. Citing CoinMarketCap, Crypto Times put ARRR between $0.27 and $0.28 on the morning of 15 October, with no sharp move after the first notice. At 08:20 UTC on 16 October, CoinGecko showed $0.2612, with a 24-hour range of $0.2490 to $0.2779 and a market cap of $51.2 million. CoinMarketCap showed $0.2352 and a range of $0.2241 to $0.2644. The two disagree because ARRR trades on thin, scattered order books, mostly ARRR/USDT pairs on MEXC, NonKYC and Gate, at a time when transfers are blocked.

Our reading, which is analysis rather than fact: a 20% dilution has not been priced in because the minted coins cannot reach most order books while exchanges keep deposits closed. Holders already on exchanges cannot withdraw either. The price on screen comes from a market with its doors shut. How much of the 39.8 million reaches order books once deposits reopen, if the coins are still valid by then, is the question the current price does not answer.

The rest of the privacy sector did not follow. At 07:59 UTC on 16 October, Coindaro’s market data showed ZEC at $1,231, up 11.9% over 24 hours, and Monero at $566.1, up 3.9%. ARRR is far from the $16.90 record it set on 23 April 2021, down about 98.6% according to CoinMarketCap.

Zcash, Monero and Bitcoin inflation bugs were caught before anyone used them, with one exception

An inflation bug is a flaw in the rules that check new coins, letting someone create coins outside the issuance schedule. On a transparent chain anyone can add up the supply and see it. On a private chain balances are hidden, which is why Zcash, and now Pirate Chain, rely on turnstiles. Several large networks have had such bugs. Almost all were fixed before anyone exploited them.

The 2010 Bitcoin case is the only other one on this list that was actually used, and it was undone within a day because the network was tiny and the fix was quick. Bitcoin’s chain was in effect rolled back, which Pirate Chain now says it cannot do.

The Zcash episode matters most for Pirate Chain, because Pirate inherits Zcash cryptography. When Zcash disclosed its counterfeiting flaw on 5 February 2019, it said Horizen and Komodo had been told privately on 13 November 2018. The XRP Ledger case is the freshest comparison: the bug was reported through a bounty and fixed before disclosure, as we described in our report on the XRP Ledger overflow bug.

Pirate Chain’s case differs on two counts: its bug was used, and the forged coins are hidden by design. The team found no sign that its shielded cryptography failed. If the GitHub fixes describe the attack, the entry point was older import-checking code that changed in the 6.0.0 release, the same release that brought Ironwood.

What it means for ARRR holders and for exchanges

For now the team asks users not to move funds, and exchange deposits and withdrawals stay paused. As described by the team, the exploit created new coins rather than taking existing ones, and it found no sign that keys or shielded cryptography were compromised. The open risk for holders is dilution and whatever the recovery plan decides about which coins count.

Access is a second question, especially in Europe. Privacy coins are already rare on regulated platforms. Under the EU anti-money-laundering regulation, crypto-asset service providers will not be allowed to hold or handle anonymity-enhancing coins from 10 July 2027, as listed in our page on the AMLR deadline. On CoinGecko, ARRR trades mainly on MEXC, NonKYC and Gate.

Nothing here is advice to buy, sell or hold ARRR. The price shown on aggregators while transfers are frozen may not be a price anyone can trade at.

Pirate Chain exploit timeline

Open questions before the post-mortem

Much is still unknown. Nobody has said who ran the exploit, or whether the attacker still controls the coins. The block heights and transactions involved have not been published. The size of the NonKYC deposit, and whether any other coins reached exchanges, is not public either.

The bigger unknown is the recovery plan. Options range from a hard fork that invalidates or quarantines the minted coins to a migration to a fresh pool, or doing nothing. Any of them needs social consensus among miners, notaries and exchanges, and none has been announced. Some outlets still describe the rollback as under way; that is out of date since the 16:46 UTC update on 15 October.

Next comes the post-mortem, which the team says will bring “further technical details and recovery instructions”. A signed 6.0.10 release would show which fixes the project adopts officially; beta3 has been on the dev branch since 16:14 UTC on 15 October. After that, watch for dPoW notarizations, mining pools and exchange deposits to restart. No date has been given for any of it.