CVE Database›Document archive›CVE-2020-12400

CVE-2020-12400

nss: P-384 and P-521 implementation uses a side-channel vulnerable modular inversion function

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Severity

Moderate

Red Hat Product Security

4.4

CVSS 3.1

Review impact separately from score.

Published · July 28, 2020

Updated · August 20, 2026

Description

A side-channel flaw was found in NSS, in the way P-384 and P-521 curves are used in the generation of EDSA signatures, leaking partial information about the ECDSA nonce. Given a small number of ECDSA signatures, this information can be used to steal the private key. The highest threat from this vulnerability is to data confidentiality.

Statement

This is a side-channel attack that can be used to exact pirate keys when ECDSA signatures are being generated. This attack is only feasible when the attacker is local to the machine or in certain cross-VM scenarios where the signature is being generated. Attacks over the network or via the internet are not feasible.

CVSS score applicability

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.

CVSS / CWE

CVSS 3.1 · 4.4
CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:N/A:N

CWE-327 · Use of a Broken or Risky Cryptographic Algorithm