CVE Database›CVE-2020-6829

CVE-2020-6829

nss: Side channel attack on ECDSA signature generation

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Severity

Moderate

Red Hat Product Security

4.4

CVSS 3.1

Review impact separately from score.

Published · June 2, 2020

Updated · August 20, 2026

Description

A flaw was found in nss. Using the EM side-channel, it is possible to extract the position of zero and non-zero wNAF digits while nss-certutil tool performs scalar multiplication during the ECDSA signature generation, 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 which can 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