# CVE-2026-82407: Klever-Go: Validator registration accepts an unvalidated BLS public key → consensus liveness DoS

> Attackers can submit invalid BLS keys to halt consensus, causing network downtime in Klever-Go blockchain nodes.

- **Severity:** High 7.0 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H`)
- **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:** 23 Sep 2026
- **Also known as:** GHSA-9wh6-9hq7-9688, GO-2026-6586

## What is CVE-2026-82407?

CVE-2026-82407 is a high-severity denial of service 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, core/kapp/validators/validators.go Register and the runtime validator update path accept a submitted BLSPublicKey without curve, prime-order subgroup, or nonzero validation. When a validator with a malformed key becomes eligible and is selected into a consensus group, MultiSigner.Reset and the corresponding signature verification creation path cannot deserialize the group key and cancel the slot. This causes repeated missed rounds and throughput degradation, and a network whose consensus group equals the eligible validator set can halt completely. Genesis validation is not affected because that path already performs CheckPublicKeyValid. This issue is fixed in version 1.7.20.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-82407?

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-2026-82407?

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

## Is CVE-2026-82407 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-82407 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-82407 and fix it if it is affected.

What it is: CVE-2026-82407 is a high-severity denial of service 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-2026-82407 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-2026-82407/ (Markdown: https://insights.sbomify.com/CVE-2026-82407/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-82407
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-82407
- OSV: https://osv.dev/vulnerability/CVE-2026-82407

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-82407/
Summaries are generated and may contain mistakes; the official description above is the record.