Onchain data has uncovered a Zcash matching bug that erased roughly 140 RUNE — THORChain's native token — from the bonds of 18 node operators. User and vault funds were unaffected, and native ZEC trading remains frozen until a fix ships.

Bonded collateral absorbed the Zcash vault slash

The slash stemmed from an outbound matching problem, the protocol said in a post on X. No funds were lost, but trading remains paused until the fix arrives in v3.21.

THORChain node operators lock up RUNE as collateral, and their stake absorbs the hit when a vault fails. In this case, the bonded collateral covered a software failure, while swappers walked away unharmed. The design puts operators' locked collateral, not user deposits, in the loss path when vault software fails — the reason a matching bug surfaced as an operator-side slash rather than a shortfall in swappers' balances.

THORChain's active set grew from 87 to 103 nodes in September, according to its State of the Network report, as Cryptopolitan reported. Those nodes' bond providers will pick up streaming yield in v3.21, allowing them to send a slice of their bond yield straight to their wallets. The feature is disabled by default and will be enabled when Mimir switches it on.

Zcash trading waits for the October 23 upgrade

The repair will be part of the THORChain v3.21.0 release, according to the protocol's GitLab post. Its changelog says all outbound matching uses the same shared destination comparator, meaning a Zcash TEX address and its matching transparent address are treated as going to the same place. ZEC outbounds to TEX addresses are now queued as transparent transactions.

When Zcash's NU6.3 network upgrade is live, all transparent ZEC outbounds will also switch to v6 signing, a fleet-wide change controlled by a HALTSIGNINGZEC control.

The upgrade is set to activate at block 28,366,100, which THORChain expects to happen around 13:40 UTC on Friday, October 23. Release notes say the height is authoritative; the time is inexact. Operators have to run a private binary with security patches on top, and the release notes tell them not to build from source. That block height is the marker to watch: with v3.21 live, the frozen ZEC book can start up again, along with Solana trading and the release's other restarts.

Other paused services restart in v3.21

The release targets several paused services, including ZEC. Solana trading stopped after a new type of Solana transaction appeared, and v3.21 lets it restart. The release also fixes the App Layer flaw behind the recent attack on Rujira's FIN contract.

Limit swaps paused due to state bloat can start again as well. Fixed SwapKit affiliate fee payouts allow SwapKit to turn THORChain back on a number of integrators. Swaps without memos are priced dynamically against spam, with registration costing more as memo slots fill. Mimir can let them back in once it enables them.

Monero is omitted from v3.21. Its other fixes are pending v3.21.1, which has no date yet.

ZEC pool is one of THORChain's newest

As Cryptopolitan reported, the 3.20 upgrade arrived on August 25, 2026, with THORChain saying it moved Monero and Zcash, both privacy-focused cryptocurrencies, closer to activation, per the protocol's blog. A native ZEC liquidity pool launched in early October, and 3.20 also reintroduced support for Solana, Base, and BNB. The fix lands on one of the network's newest integrations.

THORChain had reopened on June 23 after a security overhaul that took 11 stages and 39 days to complete following a $10.7 million exploit in May 2026.