Package Instance

cryptography Vulnerable to a Subgroup Attack Due to Missing Subgroup Validation for SECT Curves
## Vulnerability Summary

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.

## Credit

This vulnerability was discovered by:
- XlabAI Team of Tencent Xuanwu Lab
- Atuin Automated Vulnerability Discovery Engine

Vulnerable OpenSSL included in cryptography wheels
pyca/cryptography's wheels include a statically linked copy of OpenSSL. The versions of OpenSSL included in cryptography 42.0.0-44.0.0 are vulnerable to a security issue. More details about the vulnerability itself can be found in https://openssl-library.org/news/secadv/20250211.txt.

If you are building cryptography source ("sdist") then you are responsible for upgrading your copy of OpenSSL. Only users installing from wheels built by the cryptography project (i.e., those distributed on PyPI) need to update their cryptography versions.

pyca/cryptography has a vulnerable OpenSSL included in cryptography wheels
pyca/cryptography's wheels include a statically linked copy of OpenSSL. The versions of OpenSSL included in cryptography 37.0.0-43.0.0 are vulnerable to a security issue. More details about the vulnerability itself can be found in https://openssl-library.org/news/secadv/20240903.txt.

If you are building cryptography source ("sdist") then you are responsible for upgrading your copy of OpenSSL. Only users installing from wheels built by the cryptography project (i.e., those distributed on PyPI) need to update their cryptography versions.