---
id: "CVE-2026-82406"
kind: "vulnerability"
aliases: ["CVE-2026-82406", "GHSA-26r5-4mm2-px5c", "GO-2026-6584"]
title: "Klever-Go: Zombie-order theft: `Buy` missing `IsClaimed` guard in native marketplace in github.com/klever-io/klever-go"
severity: "high"
cvss: 7.1
epss: 0.00341
exploited: false
status: "open"
category: "package"
products: [{"name": "github.com/klever-io/klever-go", "fixed": ["1.7.20"], "affected": "< 1.7.20", "ecosystem": "go"}]
ecosystems: ["go"]
tags: ["go", "klever-blockchain", "klever-go", "nft-marketplace", "package"]
not_affected_if: ["no-native-marketplace-use", "version-1.7.20-or-later"]
published_at: "2026-09-23T20:17:16+00:00"
first_seen_at: "2026-10-23T19:13:08+00:00"
updated_at: "2026-10-23T19:56:22+00:00"
sources: [{"source": "govuln", "url": "https://pkg.go.dev/vuln/GO-2026-6584", "first_seen_at": "2026-10-23T19:13:08+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-82406", "first_seen_at": "2026-10-23T19:13:43+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-82406", "first_seen_at": "2026-10-23T19:35:23+00:00"}]
---

# Klever-Go: Zombie-order theft: `Buy` missing `IsClaimed` guard in native marketplace in github.com/klever-io/klever-go

Klever-Go, the Go implementation of the Klever blockchain, lets a buyer place a bid on an already-claimed marketplace order, so a later bidder is debited and cannot get the NFT or a refund. The flaw is that the native marketplace Buy function skips the IsClaimed check, so an attacker-controlled seller or bidder can take funds from later bidders.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- go:github.com/klever-io/klever-go affected < 1.7.20 fixed 1.7.20

## How to check

Check the go.mod of the project for github.com/klever-io/klever-go and confirm the version is below 1.7.20.
Run: go list -m github.com/klever-io/klever-go
If the node runs on the Klever chain, confirm which klever-go version the node binary was built from.

## Fix

Upgrade github.com/klever-io/klever-go to 1.7.20 or later.
Rebuild and redeploy nodes after the upgrade.

## Timeline

- 2026-10-23T19:13:08+00:00 govuln https://pkg.go.dev/vuln/GO-2026-6584
- 2026-10-23T19:13:43+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-82406
- 2026-10-23T19:35:23+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-82406

## From the sources

Klever-Go is the Go implementation of the Klever blockchain protocol. Prior to 1.7.20, the native marketplace function core/kapp/market/market.go Buy does not check IsClaimed before accepting a bid. A seller can use the Claim seller-accept branch to settle a resting-bid auction while leaving the claimed order loadable with a future EndTime and stale CurrentBid and CurrentBidder values. A later bidder can submit a higher bid, be debited, and cause the previous bidder to receive a refund even though the NFT has already been delivered. Because Claim and CancelOrder reject the later bidder when IsClaimed is true, the later bidder cannot obtain the NFT or recover the funds. This issue is fixed in version 1.7.20.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_