CVE-2025-69287 (GCVE-0-2025-69287)

Vulnerability from cvelistv5 – Published: 2026-02-18 18:42 – Updated: 2026-02-18 19:26

Title

BSV Blockchain SDK has an Authentication Signature Data Preparation Vulnerability

Summary

The BSV Blockchain SDK is a unified TypeScript SDK for developing scalable apps on the BSV Blockchain. Prior to version 2.0.0, a cryptographic vulnerability in the TypeScript SDK's BRC-104 authentication implementation caused incorrect signature data preparation, resulting in signature incompatibility between SDK implementations and potential authentication bypass scenarios. The vulnerability was located in the `Peer.ts` file of the TypeScript SDK, specifically in the `processInitialRequest` and `processInitialResponse` methods where signature data is prepared for BRC-104 mutual authentication. The TypeScript SDK incorrectly prepared signature data by concatenating base64-encoded nonce strings (`message.initialNonce + sessionNonce`) then decoding the concatenated base64 string (`base64ToBytes(concatenatedString)`). This produced ~32-34 bytes of signature data instead of the correct 64 bytes. BRC-104 authentication relies on cryptographic signatures to establish mutual trust between peers. When signature data preparation is incorrect, signatures generated by the TypeScript SDK don't match those expected by Go/Python SDKs; cross-implementation authentication fails; and an attacker could potentially exploit this to bypass authentication checks. The fix in version 2.0.0 ensures all SDKs now produce identical cryptographic signatures, restoring proper mutual authentication across implementations.

Severity

5.4 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:L

SSVC

Exploitation: poc Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-02-18 19:26 UTC

CWE

CWE-573 - Improper Following of Specification by Caller

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 7868 records in the last 180 days details

References

2 references

URL	Tags
https://github.com/bsv-blockchain/ts-sdk/security…	x_refsource_CONFIRM
https://github.com/bsv-blockchain/ts-sdk/commit/d…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
bsv-blockchain	ts-sdk	Affected: < 2.0.0	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2025-69287

Vulnerability from fkie_nvd - Published: 2026-02-18 19:21 - Updated: 2026-06-17 10:00

Severity

5.4 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:L

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/bsv-blockchain/ts-sdk/commit/d8cf6930028372079d977138ae9eaa03ae2f50bb
	security-advisories@github.com	https://github.com/bsv-blockchain/ts-sdk/security/advisories/GHSA-vjpq-xx5g-qvmm

Impacted products

	Vendor	Product	Version

JSON

To clipboard

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        {
          "lang": "en",
          "value": "CWE-573"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

GHSA-VJPQ-XX5G-QVMM

Vulnerability from github – Published: 2026-02-17 16:13 – Updated: 2026-02-18 23:48

Summary

BSV Blockchain SDK has an Authentication Signature Data Preparation Vulnerability

Details

BRC-104 Authentication Signature Data Preparation Vulnerability

Summary

A critical cryptographic vulnerability in the TypeScript SDK's BRC-104 authentication implementation caused incorrect signature data preparation, resulting in signature incompatibility between SDK implementations and potential authentication bypass scenarios.

Details

The vulnerability was located in the Peer.ts file of the TypeScript SDK, specifically in the processInitialRequest and processInitialResponse methods where signature data is prepared for BRC-104 mutual authentication.

Vulnerable Code Locations: - ts-sdk/src/auth/Peer.ts lines 527-531 (signing) - ts-sdk/src/auth/Peer.ts lines 584-590 (verification)

Root Cause: The TypeScript SDK incorrectly prepared signature data by: 1. Concatenating base64-encoded nonce strings: message.initialNonce + sessionNonce 2. Then decoding the concatenated base64 string: base64ToBytes(concatenatedString)

This produced ~32-34 bytes of signature data instead of the correct 64 bytes.

Buggy Implementation (Before Fix):

// CRITICAL BUG: Concatenating base64 strings before decoding
data: Peer.base64ToBytes(message.initialNonce + sessionNonce)

Correct Implementation (After Fix): The fix properly decodes each base64 nonce individually, then concatenates the byte arrays:

data: [
  ...Peer.base64ToBytes(message.initialNonce),
  ...Peer.base64ToBytes(sessionNonce)
]

Why This is Critical: BRC-104 authentication relies on cryptographic signatures to establish mutual trust between peers. When signature data preparation is incorrect: - Signatures generated by the TypeScript SDK don't match those expected by Go/Python SDKs - Cross-implementation authentication fails - An attacker could potentially exploit this to bypass authentication checks

PoC

The cross-language test suite demonstrates this vulnerability:

Setup: Use identical nonces and cryptographic inputs across TypeScript, Python, and Go SDKs
Vulnerable behavior: TypeScript SDK produces different signature data than Go/Python reference implementations
Impact demonstration: Authentication attempts between TypeScript clients and Go/Python servers fail due to signature mismatch

Test Evidence:

// Buggy approach (produces ~32-34 bytes)
const concatenatedB64 = INITIAL_NONCE_B64 + SESSION_NONCE_B64;
const buggyResult = Array.from(Buffer.from(concatenatedB64, 'base64'));

// Correct approach (produces 64 bytes)
const correctResult = [...INITIAL_NONCE_BYTES, ...SESSION_NONCE_BYTES];

Base64 Padding Short Circuit Analysis:

The vulnerability occurs because base64 padding characters (=) act as early termination signals for base64 decoders. When concatenating base64 strings before decoding:

Individual nonces: Each 44-character base64 string decodes to 32 bytes
Concatenated string: 88-character string containing padding in the middle
Decoding result: Base64 decoder stops at the first = padding character, producing only 32 bytes instead of 64

Example with test data: - INITIAL_NONCE_B64: "QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUE=" (44 chars → 32 bytes) - SESSION_NONCE_B64: "QkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkI=" (44 chars → 32 bytes) - Concatenated: "QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUE=QkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkI=" - Buggy decode: Only 32 bytes (decoder stops at first =) - Correct decode: 64 bytes (32 + 32, decoded separately then concatenated)

Impact

Vulnerability Type: Cryptographic signature verification bypass

Severity: Critical (CVSS 9.1 - Critical)

Affected Systems: - TypeScript SDK clients attempting to authenticate with Go or Python SDK servers - Any BRC-104 implementation relying on cross-SDK compatibility - Mutual authentication protocols using the affected signature preparation

Who is Impacted: - Applications using the TypeScript SDK for BRC-104 authentication - Systems requiring cross-language/SDK authentication compatibility - Any peer-to-peer authentication scenarios where TypeScript clients communicate with non-TypeScript servers

Potential Attack Vectors: - Authentication bypass through signature verification failure - Man-in-the-middle attacks if authentication is silently ignored - Denial of service through failed authentication attempts

The fix ensures all SDKs now produce identical cryptographic signatures, restoring proper mutual authentication across implementations.

Severity

5.4 (Medium)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:L

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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "@bsv/sdk"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.0.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2025-69287"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-573"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-02-17T16:13:48Z",
    "nvd_published_at": "2026-02-18T19:21:42Z",
    "severity": "MODERATE"
  },
  "details": "# BRC-104 Authentication Signature Data Preparation Vulnerability\n\n### Summary\nA critical cryptographic vulnerability in the TypeScript SDK\u0027s BRC-104 authentication implementation caused incorrect signature data preparation, resulting in signature incompatibility [between SDK implementations](https://github.com/F1r3Hydr4nt/brc104-cross-language-tests) and potential authentication bypass scenarios.\n\n### Details\nThe vulnerability was located in the `Peer.ts` file of the TypeScript SDK, specifically in the `processInitialRequest` and `processInitialResponse` methods where signature data is prepared for BRC-104 mutual authentication.\n\n**Vulnerable Code Locations:**\n- `ts-sdk/src/auth/Peer.ts` lines 527-531 (signing)\n- `ts-sdk/src/auth/Peer.ts` lines 584-590 (verification)\n\n**Root Cause:**\nThe TypeScript SDK incorrectly prepared signature data by:\n1. Concatenating base64-encoded nonce strings: `message.initialNonce + sessionNonce`\n2. Then decoding the concatenated base64 string: `base64ToBytes(concatenatedString)`\n\nThis produced ~32-34 bytes of signature data instead of the correct 64 bytes.\n\n**Buggy Implementation (Before Fix):**\n```typescript\n// CRITICAL BUG: Concatenating base64 strings before decoding\ndata: Peer.base64ToBytes(message.initialNonce + sessionNonce)\n```\n\n**Correct Implementation (After Fix):**\nThe fix properly decodes each base64 nonce individually, then concatenates the byte arrays:\n```typescript\ndata: [\n  ...Peer.base64ToBytes(message.initialNonce),\n  ...Peer.base64ToBytes(sessionNonce)\n]\n```\n\n**Why This is Critical:**\nBRC-104 authentication relies on cryptographic signatures to establish mutual trust between peers. When signature data preparation is incorrect:\n- Signatures generated by the TypeScript SDK don\u0027t match those expected by Go/Python SDKs\n- Cross-implementation authentication fails\n- An attacker could potentially exploit this to bypass authentication checks\n\n### PoC\nThe cross-language test suite demonstrates this vulnerability:\n\n1. **Setup**: Use identical nonces and cryptographic inputs across TypeScript, Python, and Go SDKs\n2. **Vulnerable behavior**: TypeScript SDK produces different signature data than Go/Python reference implementations\n3. **Impact demonstration**: Authentication attempts between TypeScript clients and Go/Python servers fail due to signature mismatch\n\n**Test Evidence:**\n```typescript\n// Buggy approach (produces ~32-34 bytes)\nconst concatenatedB64 = INITIAL_NONCE_B64 + SESSION_NONCE_B64;\nconst buggyResult = Array.from(Buffer.from(concatenatedB64, \u0027base64\u0027));\n\n// Correct approach (produces 64 bytes)\nconst correctResult = [...INITIAL_NONCE_BYTES, ...SESSION_NONCE_BYTES];\n```\n\n**Base64 Padding Short Circuit Analysis:**\n\nThe vulnerability occurs because base64 padding characters (`=`) act as early termination signals for base64 decoders. When concatenating base64 strings before decoding:\n\n1. **Individual nonces:** Each 44-character base64 string decodes to 32 bytes\n2. **Concatenated string:** 88-character string containing padding in the middle\n3. **Decoding result:** Base64 decoder stops at the first `=` padding character, producing only 32 bytes instead of 64\n\n**Example with test data:**\n- `INITIAL_NONCE_B64`: `\"QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUE=\"` (44 chars \u2192 32 bytes)\n- `SESSION_NONCE_B64`: `\"QkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkI=\"` (44 chars \u2192 32 bytes)\n- **Concatenated:** `\"QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUE=QkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkI=\"`\n- **Buggy decode:** Only 32 bytes (decoder stops at first `=`)\n- **Correct decode:** 64 bytes (32 + 32, decoded separately then concatenated)\n\n### Impact\n**Vulnerability Type:** Cryptographic signature verification bypass\n\n**Severity:** Critical (CVSS 9.1 - Critical)\n\n**Affected Systems:**\n- TypeScript SDK clients attempting to authenticate with Go or Python SDK servers\n- Any BRC-104 implementation relying on cross-SDK compatibility\n- Mutual authentication protocols using the affected signature preparation\n\n**Who is Impacted:**\n- Applications using the TypeScript SDK for BRC-104 authentication\n- Systems requiring cross-language/SDK authentication compatibility\n- Any peer-to-peer authentication scenarios where TypeScript clients communicate with non-TypeScript servers\n\n**Potential Attack Vectors:**\n- Authentication bypass through signature verification failure\n- Man-in-the-middle attacks if authentication is silently ignored\n- Denial of service through failed authentication attempts\n\nThe fix ensures all SDKs now produce identical cryptographic signatures, restoring proper mutual authentication across implementations.",
  "id": "GHSA-vjpq-xx5g-qvmm",
  "modified": "2026-02-18T23:48:50Z",
  "published": "2026-02-17T16:13:48Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/bsv-blockchain/ts-sdk/security/advisories/GHSA-vjpq-xx5g-qvmm"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-69287"
    },
    {
      "type": "WEB",
      "url": "https://github.com/bsv-blockchain/ts-sdk/commit/d8cf6930028372079d977138ae9eaa03ae2f50bb"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/bsv-blockchain/ts-sdk"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "BSV Blockchain SDK has an Authentication Signature Data Preparation Vulnerability"
}

Sightings

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Nomenclature

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Confirmed: The vulnerability has been validated from an analyst's perspective.
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Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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CVE-2025-69287 (GCVE-0-2025-69287)

FKIE_CVE-2025-69287

GHSA-VJPQ-XX5G-QVMM

BRC-104 Authentication Signature Data Preparation Vulnerability

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