CVE-2024-26130

NULL pointer dereference in pkcs12.serialize_key_and_certificates method.

• CVSS 7.5
• CWE-476
• Memory Corruption
• Local

cryptography is a package designed to expose cryptographic primitives and recipes to Python developers. Starting in version 38.0.0 and prior to version 42.0.4, if `pkcs12.serialize_key_and_certificates` is called with both a certificate whose public key did not match the provided private key and an `encryption_algorithm` with `hmac_hash` set (via `PrivateFormat.PKCS12.encryption_builder().hmac_hash(…)`, then a NULL pointer dereference would occur, crashing the Python process. This has been resolved in version 42.0.4, the first version in which a `ValueError` is properly raised.

CVE

CVE-2024-26130

CWE

CWE-476

CVSS base score

7.5

Published

2024-02-21

OWASP

A05 Security Misconfiguration

Orthogonal defect classification

Checking

Code defect classification

Incorrect Functionality

Category

Memory Corruption

Subcategory

Buffer Overflows

Accessibility scope

Local

Impact

Denial of Service (DoS)

Affected component

cryptography

Fixed by upgrading

Yes

Solution

Upgrade to cryptography version 42.0.4 or later.

from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import serialization
from cryptography.hazmat.primitives.asymmetric import rsa

private_key = rsa.generate_private_key(public_exponent=65537, key_size=2048, backend=default_backend())
mismatched_public_key = rsa.generate_private_key(public_exponent=65537, key_size=2048, backend=default_backend()).public_key()

from cryptography.hazmat.primitives.serialization import pkcs12

pkcs12.serialize_key_and_certificates(
    name=b"test",
    key=private_key,
    cert=mismatched_public_key,
    encryption_algorithm=pkcs12.encryption_builder().hmac_hash(b"password"),
)

from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import serialization
from cryptography.hazmat.primitives.asymmetric import rsa

private_key = rsa.generate_private_key(public_exponent=65537, key_size=2048, backend=default_backend())
public_key = private_key.public_key()

cert_mismatched = serialization.load_pem_public_key(b"-----BEGIN PUBLIC KEY-----\n...\n-----END PUBLIC KEY-----", backend=default_backend())

try:
    from cryptography.hazmat.primitives.serialization import pkcs12

    pkcs12.serialize_key_and_certificates(
        name=b"test",
        key=private_key,
        cert=cert_mismatched,
        encryption_algorithm=pkcs12.encryption_builder().hmac_hash(b"password"),
    )
except ValueError as e:
    print(f"Caught expected ValueError: {e}")

from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import serialization
from cryptography.hazmat.primitives.asymmetric import rsa
from cryptography.hazmat.primitives.serialization import pkcs12

# Generate a valid private key
private_key = rsa.generate_private_key(public_exponent=65537, key_size=2048, backend=default_backend())

# Generate a mismatched public key (this could be done by generating another key pair)
mismatched_public_key = rsa.generate_private_key(public_exponent=65537, key_size=2048, backend=default_backend()).public_key()

# Attempt to serialize with mismatched keys and an encryption algorithm
pkcs12.serialize_key_and_certificates(
    name=b"test",
    key=private_key,
    cert=mismatched_public_key,
    encryption_algorithm=pkcs12.encryption_builder().hmac_hash(b"password"),
)

@misc{vaitp:cve202426130,
  title        = {{NULL pointer dereference in pkcs12.serialize_key_and_certificates method.}},
  author       = {Bogaerts, Fr\'ed\'eric and Ivaki, Naghmeh and Fonseca, Jos\'e},
  year         = {2024},
  note         = {VAITP Python Vulnerability Dataset, entry CVE-2024-26130},
  howpublished = {\url{https://netpack.pt/vaitp/vulnerability/CVE-2024-26130/}}
}