GHSA-hc36-c89j-5f4j bsv-sdk and bsv-wallet persist unverified certifier signatures in acquire_certificate (direct and issuance paths)
Unverified certifier signatures persisted by `acquire_certificate`Affected packagesBoth `bsv-sdk` and `bsv-wallet` are published from the [sgbett/bsv-ruby-sdk](https://github.com/sgbett/bsv-ruby-sdk) repository. The vulnerable code lives in `lib/bsv/wallet_interface/wallet_client.rb`, which is **physically shipped inside both gems** (the `bsv-wallet.gemspec` `files` list bundles the entire `lib/bsv/wallet_interface/` tree). Consumers of either gem are independently vulnerable; the two packages are versioned separately, so each has its own affected range.| Package | Affected | Patched |
| --- | --- | --- |
| `bsv-sdk` | `>= 0.3.1, < 0.8.2` | `0.8.2` |
| `bsv-wallet` | `>= 0.1.2, < 0.3.4` | `0.3.4` |Summary`BSV::Wallet::WalletClient#acquire_certificate` persists certificate records to storage **without verifying the certifier's signature** over the certificate contents. Both acquisition paths are affected:`acquisition_protocol: 'direct'` — the caller supplies all certificate fields (including `signature:`) and the record is written to storage verbatim.`acquisition_protocol: 'issuance'` — the client POSTs to a certifier URL and writes whatever signature the response body contains, also without verification.An attacker who can reach either API (or who controls a certifier endpoint targeted by the issuance path) can forge identity certificates that subsequently appear authentic to `list_certificates` and `prove_certificate`.DetailsBRC-52 requires a certificate's `signature` field to be verified against the claimed certifier's public key over a canonical hashing of `(type, subject, serialNumber, revocationOutpoint, fields)` before the certificate is trusted. The reference TypeScript SDK enforces this in `Certificate.verify()`.Direct pathThe Ruby implementation's `acquire_via_direct` path (`lib/bsv/wallet_interface/wallet_client.rb`) constructs the certificate record directly from caller-supplied fields:The returned record is then written to the storage adapter by `acquire_certificate`. No verification of `args[:signature]` against `args[:certifier]`'s public key occurs at any point in this path.Issuance path`acquire_via_issuance` POSTs to a certifier-supplied URL and parses the response body into a certificate record, which is then written to storage without verifying the returned signature. A hostile or compromised certifier endpoint — or anyone able to redirect/MITM the plain HTTP request — can therefore return an arbitrary `signature` value for any subject and have it stored as authentic. This is the same class of bypass as the direct path; it was tracked separately as finding **F8.16** in the compliance review and is closed by the same fix.Downstream impactDownstream reads via `list_certificates` and selective-disclosure via `prove_certificate` treat stored records as valid without re-verifying, so any forgery that slips past `acquire_certificate` is trusted permanently.ImpactAny caller that can invoke `acquire_certificate` — via either acquisition protocol — can forge a certificate attributed to an arbitrary certifier identity key, containing arbitrary fields, and have it persisted as authentic. Applications and downstream gems that rely on the wallet's certificate store as a source of truth for identity attributes (e.g. KYC assertions, role claims, attestations) are subject to credential forgery.This is a credential-forgery primitive, not merely a spec divergence from BRC-52.CVSS rationale`AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N` → **8.1 (High)****AV:N** — network-reachable in any wallet context that exposes `acquire_certificate` to callers.**AC:L** — low attack complexity: pass arbitrary bytes as `signature:`.**PR:L** — low privileges: any caller authorised to invoke `acquire_certificate`.**UI:N** — no user interaction required.**C:H** — forged credentials via `prove_certificate` can assert attributes about the subject.**I:H** — the wallet's credential store is polluted with attacker-controlled data.**A:N** — availability unaffected.Proof of conceptAffected versionsThe vulnerable direct-path code was introduced in commit `d14dd19` ("feat(wallet): implement BRC-100 identity certificate methods (Phase 5)") on 2026-03-27 20:35 UTC. The vulnerable issuance-path code was added one day later in `6a4d898` ("feat(wallet): implement certificate issuance protocol", 2026-03-28 04:38 UTC), which removed an earlier `raise UnsupportedActionError` and replaced it with an unverified HTTP POST.**`bsv-sdk`:** the v0.3.1 chore bump (`89de3a2`) was committed 28 minutes after `d14dd19`, so the direct-path bypass shipped in the **v0.3.1** tag. The v0.3.1 release raised `UnsupportedActionError` for the issuance path, so the issuance-path bypass first shipped in **v0.3.2** (`5a335de`). Every subsequent release up to and including **v0.8.1** is affected by at least one path, and every release from v0.3.2 onwards is affected by both. Combined affected range: `>= 0.3.1, < 0.8.2`.**`bsv-wallet`:** at the time both commits landed, the wallet gem was at version 0.1.1. The first wallet release containing any of the vulnerable code was **v0.1.2** (`5a335de`, 2026-03-30), which shipped both paths simultaneously. Every subsequent release up to and including **v0.3.3** is affected on both paths. Affected range: `>= 0.1.2, < 0.3.4`.PatchesUpgrade to `bsv-sdk >= 0.8.2` **and/or** `bsv-wallet >= 0.3.4`. Both releases ship the same fix: a new module `BSV::Wallet::CertificateSignature` (`lib/bsv/wallet_interface/certificate_signature.rb`), which builds the BRC-52 canonical preimage (`type`, `serial_number`, `subject`, `certifier`, `revocation_outpoint`, lexicographically-sorted `fields`) and verifies the certifier's signature against it via `ProtoWallet#verify_signature` with protocol ID `[2, 'certificate signature']` and counterparty = the claimed certifier's public key. Both `acquire_via_direct` and `acquire_via_issuance` now call `CertificateSignature.verify!` before returning the certificate to `acquire_certificate`, so invalid certificates raise `BSV::Wallet::CertificateSignature::InvalidError` (a subclass of `InvalidSignatureError`) and are never written to storage.Consumers should upgrade whichever gem they depend on directly; they do not need both. `bsv-wallet 0.3.4` additionally tightens its dependency on `bsv-sdk` from the stale `~> 0.4` to `>= 0.8.2, < 1.0`, which forces the known-good pairing and pulls in the sibling advisory fixes (F1.3, F5.13) tracked separately.The issuance-path fix also partially closes finding **F8.16** from the same compliance review. F8.16's second aspect — switching the issuance transport from ad-hoc JSON POST to BRC-104 AuthFetch — is not addressed here and remains deferred to a future release.Fixed in sgbett/bsv-ruby-sdk#306.WorkaroundsIf upgrading is not immediately possible:Do not expose `acquire_certificate` (either acquisition protocol) to untrusted callers.Do not invoke `acquire_certificate` with `acquisition_protocol: 'issuance'` against a certifier URL you do not fully trust, and require TLS for any such request.Treat any record returned by `list_certificates` / `prove_certificate` as unverified and perform an out-of-band BRC-52 verification against the certifier's public key before acting on it.CreditIdentified during the 2026-04-08 cross-SDK compliance review, tracked as findings F8.15 (direct path) and F8.16 (issuance path, partial).ReferencesHLR: sgbett/bsv-ruby-sdk#305Fix PR: sgbett/bsv-ruby-sdk#306Compliance review: [`.architecture/reviews/20260408-cross-sdk-compliance-review.md`](../../.architecture/reviews/20260408-cross-sdk-compliance-review.md)BRC-52 specification: https://brc.dev/52TypeScript reference: `Certificate.verify()` in `@bsv/sdk`
CVSS v3.1 score: 8.1