CVE-2020-12402

Name: CVE-2020-12402
Creator: NVD / NIST
Published: 2020-07-09T15:15:10.82+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 4.4/10EPSS 0.34%

Last modified Jun 17, 2026

CVE-2020-12402 is a medium-severity vulnerability rated 4.4/10 on the CVSS scale. During RSA key generation, bignum implementations used a variation of the Binary Extended Euclidean Algorithm which entailed significantly input-dependent flow. This allowed an attacker able to perform electromagnetic-based side channel attacks to record traces leading to the recovery of the secret primes. EPSS estimates a 0.34% chance of exploitation in the next 30 days.

Description

During RSA key generation, bignum implementations used a variation of the Binary Extended Euclidean Algorithm which entailed significantly input-dependent flow. This allowed an attacker able to perform electromagnetic-based side channel attacks to record traces leading to the recovery of the secret primes. *Note:* An unmodified Firefox browser does not generate RSA keys in normal operation and is not affected, but products built on top of it might. This vulnerability affects Firefox < 78.

Metrics

CVSS 3.1

4.4/10

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

EPSS Probability

0.34%

25.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-203

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 78.0
Fedoraproject	Fedora	32
Opensuse	Leap	15.1
Opensuse	Leap	15.2
Debian	Debian Linux	9.0

References

http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00016.htmlThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00018.htmlThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00027.htmlThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00049.htmlThird Party Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1631597Issue Tracking, Permissions Required, Vendor Advisory
https://lists.debian.org/debian-lts-announce/2020/09/msg00029.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RFL6UNFK4MG2WDXLMLFAEIUSM5EUK7CG/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UWVDJRARXNWWWTCGMM63EXLQHH2LNOXO/
https://security.gentoo.org/glsa/202007-10Third Party Advisory
https://usn.ubuntu.com/4417-1/Third Party Advisory
https://usn.ubuntu.com/4417-2/Third Party Advisory
https://www.debian.org/security/2020/dsa-4726Third Party Advisory
https://www.mozilla.org/security/advisories/mfsa2020-24/Vendor Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00016.htmlThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00018.htmlThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00027.htmlThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00049.htmlThird Party Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1631597Issue Tracking, Permissions Required, Vendor Advisory
https://lists.debian.org/debian-lts-announce/2020/09/msg00029.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RFL6UNFK4MG2WDXLMLFAEIUSM5EUK7CG/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UWVDJRARXNWWWTCGMM63EXLQHH2LNOXO/
https://security.gentoo.org/glsa/202007-10Third Party Advisory
https://usn.ubuntu.com/4417-1/Third Party Advisory
https://usn.ubuntu.com/4417-2/Third Party Advisory
https://www.debian.org/security/2020/dsa-4726Third Party Advisory
https://www.mozilla.org/security/advisories/mfsa2020-24/Vendor Advisory

Timeline

Published: Jul 9, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-12402?

How severe is CVE-2020-12402?

CVE-2020-12402 has a CVSS score of 4.4/10 (MEDIUM severity). The EPSS model estimates a 0.34% probability of exploitation in the next 30 days.

How do I fix CVE-2020-12402?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2020-12402?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST