# CVE-2026-82406: Klever-Go: Zombie-order theft: `Buy` missing `IsClaimed` guard in native marketplace

> Attackers can exploit missing state checks in the marketplace to steal funds or NFTs by bypassing claimed order restrictions.

- **Severity:** High 7.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 23 Sep 2026
- **Updated:** 24 Sep 2026
- **Also known as:** GHSA-26r5-4mm2-px5c, GO-2026-6584

## What is CVE-2026-82406?

CVE-2026-82406 is a high-severity vulnerability in klever-io klever-go, published on 23 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

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.

Weakness: CWE-841 (Improper Enforcement of Behavioral Workflow)

## Which versions are affected by CVE-2026-82406?

3 open source packages ship an affected version, including github.com/klever-io/klever-go.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/klever-io/klever-go` | Go | All versions | 1.7.20 |
| `github.com/klever-io/klever-go` | Go | All versions | 1.7.20 |
| `github.com/klever-io/klever-go` | Go | All versions | 1.7.20 |

## How do I fix CVE-2026-82406?

Upgrade github.com/klever-io/klever-go to 1.7.20 or later.

## Is CVE-2026-82406 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-82406 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-82406 and fix it if it is affected.

What it is: CVE-2026-82406 is a high-severity vulnerability in klever-io klever-go, published on 23 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-82406 exists.

Affected packages and fixed versions:
- github.com/klever-io/klever-go (Go): affected all versions; fixed in 1.7.20
- github.com/klever-io/klever-go (Go): affected all versions; fixed in 1.7.20
- github.com/klever-io/klever-go (Go): affected all versions; fixed in 1.7.20

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-82406/ (Markdown: https://insights.sbomify.com/CVE-2026-82406/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-82406
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-82406
- OSV: https://osv.dev/vulnerability/CVE-2026-82406

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-82406/
Summaries are generated and may contain mistakes; the official description above is the record.