CVE-2026-26007
Elliptic Curve Subgroup Validation Flaw in cryptography Package
Publication date: 2026-02-10
Last updated on: 2026-02-23
Assigner: GitHub, Inc.
Description
Description
CVSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| cryptography.io | cryptography | to 46.0.5 (exc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-345 | The product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability exists in the cryptography package for Python versions prior to 46.0.5. Certain functions that handle elliptic curve public keys do not verify that the provided public key point belongs to the expected prime-order subgroup of the curve. This missing validation allows an attacker to supply a public keys from a small-order subgroup.
As a result, when a victim uses these weak public keys in cryptographic operations like ECDSA signature verification or ECDH key negotiation, it can leak information about the victim's private key or allow signature forgery on the small subgroup. Specifically, for curves with cofactor greater than 1, this can reveal the least significant bits of the private key.
Only SECT curves are affected by this vulnerability, and it was fixed in version 46.0.5 of the cryptography package.
How can this vulnerability impact me? :
This vulnerability can lead to serious security issues including leakage of private key information and the ability to forge digital signatures.
- In ECDH key negotiation, an attacker can learn information about the victim's private key modulo the small subgroup order, potentially exposing parts of the private key.
- In ECDSA signature verification, an attacker can forge signatures on the small subgroup, compromising the integrity of digital signatures.
Overall, this can undermine the confidentiality and authenticity guarantees provided by cryptographic operations using the affected functions and curves.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
I don't know
How can this vulnerability be detected on my network or system? Can you suggest some commands?
I don't know
What immediate steps should I take to mitigate this vulnerability?
To mitigate this vulnerability, upgrade the cryptography package to version 46.0.5 or later, where the issue has been fixed.