---
id: CVE-2020-12401
title: >-
  During ECDSA signature generation, padding applied in the nonce designed to
  ensure constant-time scalar multiplication was removed, resulting in
  variable-time execution dependent on secret data
summary: >-
  During ECDSA signature generation, padding applied in the nonce designed to
  ensure constant-time scalar multiplication was removed, resulting in
  variable-time execution dependent on secret data. This vulnerability affects
  Firefox < 80 an…
severity: medium
cvss: 4.7
cvssVector: 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N'
cwe:
  - CWE-203
vendor: mozilla
product: firefox
affected:
  - firefox < 80.0
  - firefox_mobile < 80.0
patched:
  - firefox 80.0
  - firefox_mobile 80.0
published: '2020-10-08'
updated: '2026-08-19'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2020-12401'
references:
  - url: 'https://bugzilla.mozilla.org/show_bug.cgi?id=1631573'
    label: security@mozilla.org
  - url: 'https://lists.debian.org/debian-lts-announce/2023/02/msg00021.html'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2020-36/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2020-39/'
    label: security@mozilla.org
  - url: 'https://bugzilla.mozilla.org/show_bug.cgi?id=1631573'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://lists.debian.org/debian-lts-announce/2023/02/msg00021.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://www.mozilla.org/security/advisories/mfsa2020-36/'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://www.mozilla.org/security/advisories/mfsa2020-39/'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.00323
epssPercentile: 0.25572
ingestedAt: '2026-08-19T15:41:14.706Z'
---

## Overview

During ECDSA signature generation, padding applied in the nonce designed to ensure constant-time scalar multiplication was removed, resulting in variable-time execution dependent on secret data. This vulnerability affects Firefox < 80 and Firefox for Android < 80.

## Affected

- `firefox < 80.0`
- `firefox_mobile < 80.0`

## Remediation

Upgrade past the affected range:

- `firefox 80.0`
- `firefox_mobile 80.0`