cryptography is a package designed to expose cryptographic primitives and recipes to Python developers. Prior to 46.0.5, the public_key_from_numbers (or EllipticCurvePublicNumbers.public_key()), EllipticCurvePublicNumbers.public_key(), load_der_public_key() and load_pem_public_key() functions do not verify that the point belongs to the expected prime-order subgroup of the curve. This missing validation allows an attacker to provide a public key point P from a small-order subgroup. This can lead to security issues in various situations, such as the most commonly used signature verification (ECDSA) and shared key negotiation (ECDH). When the victim computes the shared secret as S = [victim_private_key]P via ECDH, this leaks information about victim_private_key mod (small_subgroup_order). For curves with cofactor > 1, this reveals the least significant bits of the private key. When these weak public keys are used in ECDSA , it's easy to forge signatures on the small subgroup. Only SECT curves are impacted by this. This vulnerability is fixed in 46.0.5.

A flaw was found in OpenSSL's handling of the properties argument in certain functions. This vulnerability can allow use-after-free exploitation, which may result in undefined behavior or incorrect property parsing, leading to OpenSSL treating the input as an empty string.

A flaw was found in PyO3. This vulnerability causes a use-after-free issue, potentially leading to memory corruption or crashes via unsound borrowing from weak Python references.

A timing-based side-channel exists in the rust-openssl package, which could be sufficient to recover a plaintext across a network in a Bleichenbacher-style attack. To achieve successful decryption, an attacker would have to be able to send a large number of trial messages for decryption. The vulnerability affects the legacy PKCS#1v1.5 RSA encryption padding mode.