CVE-2023-50782

Flaw in python-cryptography allows decryption of TLS messages via RSA.

• CVSS 7.5
• CWE-203
• Cryptographic
• Remote

A flaw was found in the python-cryptography package. This issue may allow a remote attacker to decrypt captured messages in TLS servers that use RSA key exchanges, which may lead to exposure of confidential or sensitive data.

CVE

CVE-2023-50782

CWE

CWE-203

CVSS base score

7.5

Published

2024-02-05

OWASP

A02 Cryptographic Failures

Orthogonal defect classification

Algorithm

Code defect classification

Incorrect Algorithm

Category

Cryptographic

Subcategory

Improper SSL/TLS Certificate Validation

Accessibility scope

Remote

Impact

Information Disclosure

Affected component

python-crypt

Fixed by upgrading

Yes

Solution

Upgrade to python-cryptography version 3.4.8 or later.

from cryptography.hazmat.primitives.asymmetric import rsa, padding
from cryptography.hazmat.primitives import hashes

private_key = rsa.generate_private_key(
    public_exponent=65537,
    key_size=1024
)

public_key = private_key.public_key()

message = b"Sensitive data"
ciphertext = public_key.encrypt(
    message,
    padding.PKCS1v15()
)

decrypted_message = private_key.decrypt(
    ciphertext,
    padding.PKCS1v15()
)

print(decrypted_message)

from cryptography.hazmat.primitives.asymmetric import rsa, padding
from cryptography.hazmat.primitives import hashes

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

public_key = private_key.public_key()

message = b"Sensitive data"
ciphertext = public_key.encrypt(
    message,
    padding.OAEP(
        mgf=padding.MGF1(algorithm=hashes.SHA256()),
        algorithm=hashes.SHA256(),
        label=None
    )
)

decrypted_message = private_key.decrypt(
    ciphertext,
    padding.OAEP(
        mgf=padding.MGF1(algorithm=hashes.SHA256()),
        algorithm=hashes.SHA256(),
        label=None
    )
)

print(decrypted_message)

I cannot provide you with an exploit payload for CVE-2023-50782.  Sharing such information would be irresponsible and could be used for malicious purposes.  My purpose is to be helpful and harmless, and providing exploit code directly contradicts that principle.

@misc{vaitp:cve202350782,
  title        = {{Flaw in python-cryptography allows decryption of TLS messages via RSA.}},
  author       = {Bogaerts, Fr\'ed\'eric and Ivaki, Naghmeh and Fonseca, Jos\'e},
  year         = {2024},
  note         = {VAITP Python Vulnerability Dataset, entry CVE-2023-50782},
  howpublished = {\url{https://netpack.pt/vaitp/vulnerability/CVE-2023-50782/}}
}