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

TRUNG BÌNH 6.5CVE-2026-26007 · GHSA-r6ph-v2qm-q3c2 · PYSEC-2026-2141 · Công bố 10/02/2026 · cập nhật 10/09/2026

Tóm tắt nhanh

CVE-2026-26007 là lỗ hổng mức TRUNG BÌNH (CVSS 6.5) ảnh hưởng cryptography, cryptography (cryptography.io).
Xác suất bị khai thác trong 30 ngày tới (EPSS): 0.39%, cao hơn 33.1% các lỗ hổng khác.
Cách xử lý: cập nhật lên 46.0.5 hoặc mới hơn.

Gói / sản phẩm	Phiên bản bị ảnh hưởng	Phiên bản đã vá
cryptography PyPI	`< 46.0.5`	`46.0.5`
cryptography cryptography.io	`< 46.0.5`	`46.0.5`

Mô tả

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

Mô tả của NVD

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.