CVE-2020-12401

Severity: medium (CVSS 4.7 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2020-10-08 · updated 2026-08-19
Weakness: CWE-203

Description

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 products

Mozilla Firefox: before 80.0 — fixed in 80.0
Mozilla Firefox for Android: before 80.0 — fixed in 80.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 80.0; Mozilla Firefox for Android 80.0. Check the vendor advisory for mitigations.

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1631573
https://lists.debian.org/debian-lts-announce/2023/02/msg00021.html
https://www.mozilla.org/security/advisories/mfsa2020-36/
https://www.mozilla.org/security/advisories/mfsa2020-39/
https://bugzilla.mozilla.org/show_bug.cgi?id=1631573
https://lists.debian.org/debian-lts-announce/2023/02/msg00021.html
https://www.mozilla.org/security/advisories/mfsa2020-36/
https://www.mozilla.org/security/advisories/mfsa2020-39/

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