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

Type: advisorySource: OSV1 source record

**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.BLS12_381)` 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/`). `CheckPublicKeyValid` — which does `IsValid && IsValidOrder && !IsZero` — runs only at genesis, not on runtime registration/update. ### POC Attack: (1) stake the minimum to register a validator, submitting a 96-byte `BLSPublicKey` that is not a valid G2 point (arbitrary bytes). Registration succeeds. (2) Once the validator is eligible and selected into a consensus group, every in-group node including the honest leader (`group[0]`) calls `MultiSigner().Reset(grou

Announced Source revision 1
Original source ↗

GHSA-9wh6-9hq7-9688

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: osv:GHSA-9wh6-9hq7-9688

github.com/klever-io/klever-go

Source reference: /affected/0/package/name

Affected versions
Not stated in this record
Fixed versions
1.7.20

Source reference: /affected/0/ranges

Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "ranges": [
      {
        "type": "SEMVER",
        "events": [
          {
            "introduced": "0"
          },
          {
            "fixed": "1.7.20"
          }
        ]
      }
    ],
    "package": {
      "name": "github.com/klever-io/klever-go",
      "purl": "pkg:golang/github.com/klever-io/klever-go",
      "ecosystem": "Go"
    },
    "database_specific": {
      "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-9wh6-9hq7-9688/GHSA-9wh6-9hq7-9688.json",
      "last_known_affected_version_range": "<= 1.7.19"
    }
  }
]
Related CVEs
CVE-2026-82407

Source reference: /aliases

Publisher severity

high

Source reference: /database_specific/severity

Event
#63962 · Revision 1
Added to Heist Feed
Publisher date
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