CVE-2026-55763

Klever-Go is the Go implementation of the Klever blockchain protocol. Prior to 1.7.19, processPercentageRoyaltiesTransfer in core/kapp/accounts/accounts.go calls SubFromBalance after the split loop and after the royaltiesToPay <= 0 early return. computeSplitRoyalties rejects only when splitToPay > royaltiesToPay, so a valid PercentTransferPercentage = 10000 split consumes exactly 100 percent of the royalty pool, sets royaltiesToPay to zero, and returns before the source account is debited. The split recipient receives the full royaltyAmount while the sender pays nothing and the supply counter is not updated, allowing unbounded off-the-books inflation of the transferred KDA. A KDA owner must configure a TransferPercentage royalty with a 100 percent split, after which any holder's transfer of the asset triggers the mint; the sibling processFixedRoyaltiesTransfer path is not affected because it debits the source before distribution. This issue is fixed in version 1.7.19.

Klever-Go is the Go implementation of the Klever blockchain protocol. Prior to 1.7.19, processPercentageRoyaltiesTransfer in core/kapp/accounts/accounts.go calls SubFromBalance after the split loop and after the royaltiesToPay <= 0 early return. computeSplitRoyalties rejects only when splitToPay > royaltiesToPay, so a valid PercentTransferPercentage = 10000 split consumes exactly 100 percent of the royalty pool, sets royaltiesToPay to zero, and returns before the source account is debited. The split recipient receives the full royaltyAmount while the sender pays nothing and the supply counter is not updated, allowing unbounded off-the-books inflation of the transferred KDA. A KDA owner must configure a TransferPercentage royalty with a 100 percent split, after which any holder's transfer of the asset triggers the mint; the sibling processFixedRoyaltiesTransfer path is not affected because it debits the source before distribution. This issue is fixed in version 1.7.19.

Summary

In processPercentageRoyaltiesTransfer the royalty pool is collected from the sender by SubFromBalance that is ordered after the split loop and after if royaltiesToPay <= 0 { return Ok }. The split-payout guard rejects only an allocation that exceeds the pool (a strict splitToPay > royaltiesToPay), so a split entry of exactly 100% (PercentTransferPercentage = 10000) is a valid config: it drives royaltiesToPay to 0 and hits the early-return before the sender is debited. The split recipient keeps the full royalty; the sender pays nothing for it → mint. The sibling fixed-royalty path (processFixedRoyaltiesTransfer) debits the sender first and is safe. Only the percentage-transfer path collects and distributes in the same function with the collect placed after the early-return.

Affected code

• core/kapp/accounts/accounts.go — processPercentageRoyaltiesTransfer: split loop → if royaltiesToPay <= 0 { return Ok } → acntSrc.SubFromBalance(royaltyAmount) (debit after the early-return). Contrast the safe processFixedRoyaltiesTransfer (debit before the loop).

Impact

Unbounded self-inflation of the transferred KDA: royaltyAmount = transferValue × rate is minted to an owner-controlled split address on every transfer of the asset, with no source debit and no supply-counter update (off-the-books).

Reachability

Owner-gated to configure (own KDA with a TransferPercentage royalty + a 100% split). Once configured, the mint fires on any holder's transfer of the asset — not just the owner's.

Proof of concept

Unit test

TestExploit_PercentRoyaltyZeroDebit drives the real processPercentageRoyaltiesTransfer with all relevant forks ON (KdaFpr, EnableSmartContracts, FixMarketBuyOverflow). With a single 100% split the recipient is credited the full royalty (40) while the sender's SubFromBalance is called 0 times (mint = 40); the 50% control case does not early-return, the sender is debited, and value conserves.

<details><summary>Full Go PoC (<code>core/kapp/accounts</code> package, passes = mint confirmed)</summary>

package accounts

import (
	"bytes"
	"encoding/hex"
	"testing"

	"github.com/stretchr/testify/require"

	commonMock "github.com/klever-io/klever-go/common/mock"
	"github.com/klever-io/klever-go/core"
	"github.com/klever-io/klever-go/core/kapp"
	"github.com/klever-io/klever-go/data/block"
	"github.com/klever-io/klever-go/data/state"
	"github.com/klever-io/klever-go/data/transaction"
	integrationMock "github.com/klever-io/klever-go/integrationTest/mock"
	"github.com/klever-io/klever-go/kapps"
	kvmStub "github.com/klever-io/klever-go/kvm/mock/stub"
)

// TestExploit_PercentRoyaltyZeroDebit proves the zero-debit mint:
// processPercentageRoyaltiesTransfer credits the split recipient
// inside the loop, then hits `if royaltiesToPay <= 0 { return Ok }` BEFORE the
// sender's `acntSrc.SubFromBalance(royaltyAmount, ...)`. A single VALID split
// entry of exactly 100% (PercentTransferPercentage = 10000) drives royaltiesToPay
// to 0 and skips the debit => the recipient keeps royaltyAmount, the sender pays
// nothing => mint. The sibling fixed path debits FIRST, so the 50% contrast case
// (which does NOT early-return) confirms the debit fires and value is conserved.
func TestExploit_PercentRoyaltyZeroDebit(t *testing.T) {
	const (
		assetIDStr     = "FUNGI-1234"
		transferValue  = int64(800)
		royaltyRatePct = uint32(500) // 5%
		royaltyAmount  = int64(40)   // 800 * 5% = 40
	)

	assetID := []byte(assetIDStr)

	// 32-byte, non-zero-prefixed => not a smart-contract address, so the royalty
	// path is not short-circuited by core.IsSmartContractAddress.
	senderAddr := bytes.Repeat([]byte{0x11}, 32)
	// Split recipient address must be a valid hex string (computeSplitRoyalties
	// hex-decodes the map key).
	recipientAddr := bytes.Repeat([]byte{0x22}, 32)
	recipientKey := hex.EncodeToString(recipientAddr)
	royaltyReceiverAddr :=…

Klever-Go is the Go implementation of the Klever blockchain protocol. Prior to 1.7.19, processPercentageRoyaltiesTransfer in core/kapp/accounts/accounts.go calls SubFromBalance after the split loop and after the royaltiesToPay <= 0 early return. computeSplitRoyalties rejects only when splitToPay > royaltiesToPay, so a valid PercentTransferPercentage = 10000 split consumes exactly 100 percent of the royalty pool, sets royaltiesToPay to zero, and returns before the source account is debited. The split recipient receives the full royaltyAmount while the sender pays nothing and the supply counter is not updated, allowing unbounded off-the-books inflation of the transferred KDA. A KDA owner must configure a TransferPercentage royalty with a 100 percent split, after which any holder's transfer of the asset triggers the mint; the sibling processFixedRoyaltiesTransfer path is not affected because it debits the source before distribution. This issue is fixed in version 1.7.19.

Klever-Go is the Go implementation of the Klever blockchain protocol. Prior to 1.7.19, processPercentageRoyaltiesTransfer in core/kapp/accounts/accounts.go calls SubFromBalance after the split loop and after the royaltiesToPay <= 0 early return. computeSplitRoyalties rejects only when splitToPay > royaltiesToPay, so a valid PercentTransferPercentage = 10000 split consumes exactly 100 percent of the royalty pool, sets royaltiesToPay to zero, and returns before the source account is debited. The split recipient receives the full royaltyAmount while the sender pays nothing and the supply counter is not updated, allowing unbounded off-the-books inflation of the transferred KDA. A KDA owner must configure a TransferPercentage royalty with a 100 percent split, after which any holder's transfer of the asset triggers the mint; the sibling processFixedRoyaltiesTransfer path is not affected because it debits the source before distribution. This issue is fixed in version 1.7.19.

Summary

In processPercentageRoyaltiesTransfer the royalty pool is collected from the sender by SubFromBalance that is ordered after the split loop and after if royaltiesToPay <= 0 { return Ok }. The split-payout guard rejects only an allocation that exceeds the pool (a strict splitToPay > royaltiesToPay), so a split entry of exactly 100% (PercentTransferPercentage = 10000) is a valid config: it drives royaltiesToPay to 0 and hits the early-return before the sender is debited. The split recipient keeps the full royalty; the sender pays nothing for it → mint. The sibling fixed-royalty path (processFixedRoyaltiesTransfer) debits the sender first and is safe. Only the percentage-transfer path collects and distributes in the same function with the collect placed after the early-return.

Affected code

• core/kapp/accounts/accounts.go — processPercentageRoyaltiesTransfer: split loop → if royaltiesToPay <= 0 { return Ok } → acntSrc.SubFromBalance(royaltyAmount) (debit after the early-return). Contrast the safe processFixedRoyaltiesTransfer (debit before the loop).

Impact

Unbounded self-inflation of the transferred KDA: royaltyAmount = transferValue × rate is minted to an owner-controlled split address on every transfer of the asset, with no source debit and no supply-counter update (off-the-books).

Reachability

Owner-gated to configure (own KDA with a TransferPercentage royalty + a 100% split). Once configured, the mint fires on any holder's transfer of the asset — not just the owner's.

Proof of concept

Unit test

TestExploit_PercentRoyaltyZeroDebit drives the real processPercentageRoyaltiesTransfer with all relevant forks ON (KdaFpr, EnableSmartContracts, FixMarketBuyOverflow). With a single 100% split the recipient is credited the full royalty (40) while the sender's SubFromBalance is called 0 times (mint = 40); the 50% control case does not early-return, the sender is debited, and value conserves.

<details><summary>Full Go PoC (<code>core/kapp/accounts</code> package, passes = mint confirmed)</summary>

package accounts

import (
	"bytes"
	"encoding/hex"
	"testing"

	"github.com/stretchr/testify/require"

	commonMock "github.com/klever-io/klever-go/common/mock"
	"github.com/klever-io/klever-go/core"
	"github.com/klever-io/klever-go/core/kapp"
	"github.com/klever-io/klever-go/data/block"
	"github.com/klever-io/klever-go/data/state"
	"github.com/klever-io/klever-go/data/transaction"
	integrationMock "github.com/klever-io/klever-go/integrationTest/mock"
	"github.com/klever-io/klever-go/kapps"
	kvmStub "github.com/klever-io/klever-go/kvm/mock/stub"
)

// TestExploit_PercentRoyaltyZeroDebit proves the zero-debit mint:
// processPercentageRoyaltiesTransfer credits the split recipient
// inside the loop, then hits `if royaltiesToPay <= 0 { return Ok }` BEFORE the
// sender's `acntSrc.SubFromBalance(royaltyAmount, ...)`. A single VALID split
// entry of exactly 100% (PercentTransferPercentage = 10000) drives royaltiesToPay
// to 0 and skips the debit => the recipient keeps royaltyAmount, the sender pays
// nothing => mint. The sibling fixed path debits FIRST, so the 50% contrast case
// (which does NOT early-return) confirms the debit fires and value is conserved.
func TestExploit_PercentRoyaltyZeroDebit(t *testing.T) {
	const (
		assetIDStr     = "FUNGI-1234"
		transferValue  = int64(800)
		royaltyRatePct = uint32(500) // 5%
		royaltyAmount  = int64(40)   // 800 * 5% = 40
	)

	assetID := []byte(assetIDStr)

	// 32-byte, non-zero-prefixed => not a smart-contract address, so the royalty
	// path is not short-circuited by core.IsSmartContractAddress.
	senderAddr := bytes.Repeat([]byte{0x11}, 32)
	// Split recipient address must be a valid hex string (computeSplitRoyalties
	// hex-decodes the map key).
	recipientAddr := bytes.Repeat([]byte{0x22}, 32)
	recipientKey := hex.EncodeToString(recipientAddr)
	royaltyReceiverAddr :=…