CVE-2026-26007

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.

What this means for your business

It affects Cryptography.Io Cryptography. It matters if your company, or a supplier that handles your data, runs it.
An attacker can use it remotely, over a network, without a login, but only after tricking someone into an action such as opening a file or a link.
FIRST's prediction model gives it a 0.3% chance of attack attempts being seen in the next 30 days, ranking above 28% of all known flaws.

What to do

1Check whether your company or your suppliers run Cryptography.Io Cryptography, and which version. The affected versions are listed further down this page.
2If you do, apply the vendor's fix. A patch or vendor advisory has been published.

Not sure if your company is exposed?

Fastnexa’s certified penetration testers can check whether attackers could use this flaw, or others like it, against your websites, apps and network. The full test is free for our first 10 founding clients until 31 December 2026.

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Scoring

CVSS: 6.5 (v3.1)
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
CVSS v4: 8.2
Weakness: CWE-345
Assigned by: security-advisories@github.com

Dates

Published: 2026-02-10
Last modified: 2026-09-10
Sources: NVD

Affected products

Cryptography.Io Cryptography- 46.0.5

As listed in the NVD configuration data. Not a statement about your estate.