CVE-2026-82407

**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(groupPubKeys, selfIndex)` at slot start, which deserializes all group keys via `PublicKeyFromByteArray` → herumi `Deserialize` **deterministically fails** on the malformed key → `SetSlotCanceled(true)`. The verify side (`Create(consensusPubKeys)`) fails identically. No block is produced for that round. ### Impact Every consensus round whose group contains the malformed-key validator is a missed slot. One eligible bad-key validator poisons roughly a `groupSize / eligibleSet` fraction o