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High, CVSS 7.0amended

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

CVE-2026-82407GHSA-9wh6-9hq7-9688

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (github.com/klever-io/klever-go 1.7.20), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
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 · score source
EPSS
  • CVE-2026-82407: 0.47% estimated exploitation activity in the next 30 days; percentile 40.38 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Location: core/kapp/validators/validators.go:201 (Register), (genesis/checking/nodesSetupChecker.go:73). core/consensus/slot/bls/subslotStartSlot.go:165 core/consensus/.../headerSignatureVerify.go:123 (Create(...)). Description Klever uses a BDN (Boneh-Drijvers-Neven) BLS multi-signature over BLS12-381 to finalize blocks (crypto/signing/mcl/multisig/bls.go, herumi/bls-go-binary). The library is initialized with only bls.Init(bls.BLS12381) and no order-verification flags, so Deserialize does not enforce prime-order-subgroup membership subgroup safety relies on explicit IsValidOrder() calls in the wrappers. Runtime validator registration (validators.Register) stores the submitted 96-byte BLSPublicKey via SetBLSPublicKey with no curve check, no subgroup check, and no proof-of-possession (CreateValidatorContract carries the key but no signature proving key ownership; grep confirms no proofOfPossession/VerifyProof/BLSSignature verification anywhere in core/kapp/validators/).…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 4 · amended ·

    Amended from ghsa record GHSA-9wh6-9hq7-9688

  2. Revision 3 · amended ·

    Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

  3. Revision 2 · amended ·

    Amended from osv record GO-2026-6586

  4. Revision 1 · created ·

    Published from osv record GHSA-9wh6-9hq7-9688

Agent brief

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# Patch Next advisory brief: CVE-2026-82407

Advisory: Klever-Go: Validator registration accepts an unvalidated BLS public key → consensus liveness DoS
IDs: CVE-2026-82407, GHSA-9wh6-9hq7-9688
Record: https://patchnext.com/advisories/cve-2026-82407 (revision 4, source checked 26 Oct 2026, 15:29 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.0)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/klever-io/klever-go 1.7.20. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/klever-io/klever-go: affected <= 1.7.19; fixed in 1.7.20

## Suggested inspection (read-only)
- Go github.com/klever-io/klever-go: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/klever-io/klever-go.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GO-2026-6586 (OSV record GO-2026-6586 lists affected ranges: Go github.com/klever-io/klever-go >=0 <1.7.20 (fixed))
- Verified: https://osv.dev/vulnerability/GHSA-9wh6-9hq7-9688 (OSV record GHSA-9wh6-9hq7-9688 lists affected ranges: Go github.com/klever-io/klever-go >=0 <1.7.20 (fixed))
- Verified: https://github.com/advisories/GHSA-9wh6-9hq7-9688 (GitHub-reviewed advisory GHSA-9wh6-9hq7-9688 lists affected ranges: Go github.com/klever-io/klever-go >=0 <=1.7.19)

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