Klever-Go KVM: Throttler slot leak in trie account-data sync causes epoch bootstrap / state sync DoS

Summary

Klever-Go is the Go implementation of the Klever blockchain protocol. In versions prior to 1.7.18, the account-data trie syncers are vulnerable to a resource-exhaustion flaw that leaks bounded throttler slots on error paths. In syncDataTrie() (in both userAccountsSyncer.go and kappAccountsSyncer.go), StartProcessing() reserves a slot from the NumGoRoutinesThrottler, but the corresponding EndProcessing() is only called on the success path and on the duplicate-root early return. As a result, any error from trie.NewTrie(), trie.NewTrieSyncer(), or trieSyncer.StartSyncing() (including the network-dependent timeout path) permanently consumes one slot for the lifetime of the throttler. An attacker who can repeatedly cause trie-node sync failures or timeouts during bootstrap can exhaust the bounded throttler, after which further account-data trie syncs stop making progress and SyncAccounts() returns a timeout. Because epoch bootstrap in syncUserAccountsState() and syncKappAccountsState() aborts on any such error, this causes bootstrap to fail, a core availability issue affecting fresh, restarting, or resyncing nodes and validators. This issue is fixed in version 1.7.18.

Timeline

1. Aug 7, 2026, 10:18 PM UTCCVE published
2. Aug 13, 2026, 6:40 PM UTCCISA SSVC assessment

   Exploitation: poc · Automatable: no · Technical impact: partial

3. Aug 13, 2026, 6:40 PM UTCRecord last updated

Affected versions

• klever-io klever-go

  fixed in 1.7.18

• github.com/klever-io/klever-goGo

  fixed in 1.7.18

References 2