CVE-2026-44714: Bitcoinj core Bitcoinj Has A ScriptExecution P2PKH/P2WPKH Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-hfcf-v2f8-x9pc",
  "modified" : "2026-05-15T23:49:51Z",
  "published" : "2026-05-08T17:43:06Z",
  "aliases" : [ "CVE-2026-44714" ],
  "summary" : "bitcoinj has a ScriptExecution P2PKH/P2WPKH Verification Bypass",
  "details" : "### Summary\n`ScriptExecution.correctlySpends()` contains two fast-path verification bugs for standard `P2PKH` and native `P2WPKH` spends in `core/src/main/java/org/bitcoinj/script/ScriptExecution.java`.\n\nIn both branches, bitcoinj verifies an attacker-controlled signature/public-key pair but fails to verify that the public key is the one committed to by the output being spent. As a result, any attacker keypair can satisfy bitcoinj's local verification for arbitrary `P2PKH` and `P2WPKH` outputs.\n\nThis doesn't affect the SPV (simple payment verification) trust model, as this model follows PoW and doesn't verify input signatures at all.\n\n### Details\nThe issue is in the optimized branches of `ScriptExecution.correctlySpends(...)`.\n\nIn the `P2PKH` fast path at `core/src/main/java/org/bitcoinj/script/ScriptExecution.java:1042`, the code:\n\n- parses the attacker-supplied signature from `scriptSig`\n- parses the attacker-supplied public key from `scriptSig`\n- computes the sighash against the victim output's `scriptPubKey`\n- checks only `pubkey.verify(sigHash, signature)`\n\nIt never enforces the missing `P2PKH` binding:\n\n- `HASH160(pubkey) == ScriptPattern.extractHashFromP2PKH(scriptPubKey)`\n\nThat means the `OP_DUP OP_HASH160 <hash> OP_EQUALVERIFY OP_CHECKSIG` semantics are not actually enforced in this fast path.\n\nRelevant code:\n\n```java\n} else if (ScriptPattern.isP2PKH(scriptPubKey)) {\n    if (chunks.size() != 2)\n        throw new ScriptException(...);\n    TransactionSignature signature;\n    try {\n        byte[] data = Objects.requireNonNull(chunks.get(0).data);\n        signature = TransactionSignature.decodeFromBitcoin(data, true, true);\n    } catch (SignatureDecodeException x) {\n        throw new ScriptException(...);\n    }\n    ECKey pubkey = ECKey.fromPublicOnly(Objects.requireNonNull(chunks.get(1).data));\n    Sha256Hash sigHash = txContainingThis.hashForSignature(scriptSigIndex, scriptPubKey,\n            signature.sigHashMode(), false);\n    boolean validSig = pubkey.verify(sigHash, signature);\n    if (!validSig)\n        throw new ScriptException(...);\n}\n```\n\nIn the native `P2WPKH` fast path at `core/src/main/java/org/bitcoinj/script/ScriptExecution.java:1023`, the bug is similar. The code:\n\n- reads the attacker-supplied pubkey from `witness`\n- builds `scriptCode` from that attacker pubkey with `ScriptBuilder.createP2PKHOutputScript(pubkey)`\n- computes the BIP143 sighash using that attacker-derived `scriptCode`\n- verifies the signature against the attacker pubkey\n\nIt never enforces:\n\n- `HASH160(pubkey) == ScriptPattern.extractHashFromP2WH(scriptPubKey)`\n\nSo for `P2WPKH`, the attacker controls both the pubkey and the `scriptCode` used for signing.\n\nRelevant code:\n\n```java\nif (ScriptPattern.isP2WPKH(scriptPubKey)) {\n    Objects.requireNonNull(witness);\n    if (witness.getPushCount() < 2)\n        throw new ScriptException(...);\n    TransactionSignature signature;\n    try {\n        signature = TransactionSignature.decodeFromBitcoin(witness.getPush(0), true, true);\n    } catch (SignatureDecodeException x) {\n        throw new ScriptException(...);\n    }\n    ECKey pubkey = ECKey.fromPublicOnly(witness.getPush(1));\n    Script scriptCode = ScriptBuilder.createP2PKHOutputScript(pubkey);\n    Sha256Hash sigHash = txContainingThis.hashForWitnessSignature(scriptSigIndex, scriptCode, value,\n            signature.sigHashMode(), false);\n    boolean validSig = pubkey.verify(sigHash, signature);\n    if (!validSig)\n        throw new ScriptException(...);\n}\n```\n\nAffected call sites include:\n\n- `core/src/main/java/org/bitcoinj/core/TransactionInput.java:546`\n- `core/src/main/java/org/bitcoinj/wallet/Wallet.java:4520`\n- `core/src/main/java/org/bitcoinj/signers/LocalTransactionSigner.java:84`\n- `core/src/main/java/org/bitcoinj/signers/CustomTransactionSigner.java:77`\n\nThese call sites use `correctlySpends()` for transaction/input validation and pre-signing checks. Any application that treats a successful result from this path as proof that a spend is valid is affected.\n\n### Fix\nThe issue is fixed on the `release-0.17` branch via 2bc5653c41d260d840692bc554690d4d79208f9c, and on `master` via b575a682acf614b9ff95cacbdeb48f86c3ababe0. A 0.17.1 maintenance release has been made available on Maven Central.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.bitcoinj:bitcoinj-core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0.15"
      }, {
        "fixed" : "0.17.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/bitcoinj/bitcoinj/security/advisories/GHSA-hfcf-v2f8-x9pc"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-44714"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/bitcoinj/bitcoinj/commit/2bc5653c41d260d840692bc554690d4d79208f9c"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/bitcoinj/bitcoinj/commit/b575a682acf614b9ff95cacbdeb48f86c3ababe0"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/bitcoinj/bitcoinj"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/bitcoinj/bitcoinj/releases/tag/v0.17.1"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-347" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-08T17:43:06Z",
    "nvd_published_at" : "2026-05-15T17:16:47Z"
  }
}